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 AMERICAN SOCIETY OF CIVIL ENGINEERS Instituted 1852

 TRANSACTIONS

 Paper No. 1171

 FEDERAL INVESTIGATIONS OF MINE ACCIDENTS, STRUCTURAL MATERIALS, AND FUELS. [1]

 By HERBERT M. WILSON, M. Am. Soc. C. E. 

 With Discussion by Messrs. KENNETH ALLEN, HENRY KREISINGER, WALTER O. SNELLING, A. BARTOCCINI, H. G. STOTT, B. W. DUNN, and HERBERT M. WILSON. 

INTRODUCTION. 

The mine disaster, which occurred at Cherry, Ill. , on November 13th, 1909, when 527 men were in the mine, resulting in the entombment of 330men, of whom 310 were killed, has again focused public attention on thefrequent recurrence of such disasters and their appalling consequences. Interest in the possible prevention of such disasters, and the possiblemeans of combating subsequent mine fires and rescuing the imprisonedminers, has been heightened as it was not even by the series of threeequally extensive disasters which occurred in 1907, for the reason that, after the Cherry disaster, 20 men were rescued alive after an entombmentof one week, when practically all hope of rescuing any of the miners hadbeen abandoned. 

This accident, occurring, as it does, a little more than 1½ years afterthe enactment of legislation by Congress instructing the Director of theUnited States Geological Survey to investigate the causes and possiblemeans of preventing the loss of life in coal-mining operations, makesthis an opportune time to review what has been done by the GeologicalSurvey during this time, toward carrying out the intent of this Act. 

It may be stated with confidence, that had such a disaster occurred ayear or more ago, all the entombed men must have perished, as it wouldhave been impossible to enter the mine without the protection affordedby artificial respiratory apparatus. Moreover, but for the presence ofthe skilled corps of Government engineers, experienced by more than ayear’s training in similar operations in more than twenty disasters, themine would have been sealed until the fire had burned out, and neitherthe dead, nor those who were found alive, would have been recovered formany weeks. In the interval great suffering and loss would have beeninflicted on the miners, because of enforced idleness, and on the mineowners because of continued inability to re-open and resume operations. 

_Character of the Work. _--The United States Geological Survey has beenengaged continuously since 1904 in conducting investigations relating tostructural materials, such as stone, clay, cement, etc. , and in makingtests and analyses of the coals, lignites, and other mineral fuelsubstances, belonging to, and for the use of, the Government. 

Incidentally, the Survey has been considering means to increaseefficiency in the use of these resources as fuels and structuralmaterials, in the hope that the investigations will lead to their bestutilization. 

These inquiries attracted attention to the waste of human life incidentto the mining of fuel and its preparation for the market, with theresult that, in May, 1908, provision was made by Congress forinvestigations into the causes of mine explosions with a view to theirprevention. 

Statistics collected by the Geological Survey show that the averagedeath rate in the coal mines of the United States from accidents of allkinds, including gas and dust explosions, falls of roof, powderexplosions, etc. , is three times that of France, Belgium, or Germany. Onthe other hand, in no country in the world are natural conditions sofavorable for the safe extraction of coal as in the United States. InBelgium, foremost in the study of mining conditions, a constantreduction in the death rate has been secured, and from a rate oncenearly as great as that of the United States, namely, 3. 28 per thousand, in the period 1851-60, it had been reduced to about 2 per thousand inthe period 1881-90; and in the last decade this has been further reducedto nearly 1 per thousand. It seems certain, from the investigationsalready made by the Geological Survey, that better means of safeguardingthe lives of miners will be found, and that the death rate from mineaccidents will soon show a marked reduction. 

Other statistics collected by the Geological Survey show that, to theclose of 1907, nearly 7, 000, 000, 000 tons of coal had been mined in theUnited States, and it is estimated that for every ton mined nearly a tonhas been wasted, 3, 500, 000, 000 tons being left in the ground or thrownon the dump as of a grade too low for commercial use. To the close of1907 the production represents an exhaustion of somewhat more than10, 000, 000, 000 tons of coal. It has been estimated that if theproduction continues to increase, from the present annual output ofapproximately 415, 000, 000 tons, at the rate which has prevailed duringthe last fifty years, the greater part of the more accessible coalsupply will be exhausted before the middle of the next century. 

The Forest Service estimates that, at the present rate of consumption, renewals of growth not being taken into account, the timber supply willbe exhausted within the next quarter of a century. It is desirable, therefore, that all information possible be gained regarding the mostsuitable substitutes for wood for building and engineering construction, such as iron, stone, clay products, concrete, etc. , and that the minimumproportion in which these materials should be used for a given purpose, be ascertained. Exhaustion, by use in engineering and buildingconstruction, applies not only to the iron ore, clay, and cement-makingmaterials, but, in larger ratio, to the fuel essential to renderingthese substances available for materials of construction. Incidentally, investigations into the waste of structural materials have developed thefact that the destructive losses, due to fires in combustible buildings, amount to more than $200, 000, 000 per annum. A sum even greater than thisis annually expended on fire protection. Inquiries looking to thereduction of fire losses are being conducted in order to ascertain themost suitable fire-resisting materials for building construction. 

Early in 1904, during the Louisiana Purchase Exposition, Congress madeprovision for tests, demonstrations, and investigations concerning thefuels and structural materials of the United States. Theseinvestigations were organized subsequently as the Technologic Branch ofthe United States Geological Survey, under Mr. Joseph A. Holmes, Expertin Charge, and the President of the United States invited a group ofcivilian engineers and Chiefs of Engineering Bureaus of the Governmentto act as a National Advisory Board concerning the method of conductingthis work, with a view to making it of more immediate benefit to theGovernment and to the people of the United States. This Society isformally represented on this Board by C. C. Schneider, Past-President, Am. Soc. C. E. , and George S. Webster, M. Am. Soc. C. E. Amongrepresentatives of other engineering societies, or of GovernmentBureaus, the membership of the National Advisory Board includes othermembers of this Society, as follows: General William Crozier, Frank T. Chambers, Professor W. K. Hatt, Richard L. Humphrey, Robert W. Hunt, H. G. Kelley, Robert W. Lesley, John B. Lober, Hunter McDonald, andFrederick H. Newell. 

In view, therefore, of the important part taken both officially andunofficially by members of this Society in the planning and organizationof this work, it seems proper to present a statement of the scope, methods, and progress of these investigations. Whereas the Act governingthis work limits the testing and investigation of fuels and ofstructural materials to those belonging to the United States, theactivities of the Federal Government in the use of these materials sofar exceeds that of any other single concern in the United States, thatthe results cannot but be of great value to all engineers and to allthose engaged in engineering works. 

MINE ACCIDENTS INVESTIGATIONS. 

_Organization, and Character of the Work. _--The mine rescueinvestigations, carried on at the Federal testing station, at Pittsburg, Pa. , include five lines of attack:

1. --Investigations in the mines to determine the conditions leading upto mine disasters, the presence and the relative explosibility of minegas and coal dust, and mine fires and means of preventing and combatingthem. 

2. --Tests to determine the relative safety, or otherwise, of the variousexplosives used in coal mining, when ignited in the presence ofexplosible mixtures of natural gas and air, or coal dust, or of both. 

3. --Tests to determine the conditions under which electric equipment issafe in coal-mining operations. 

4. --Tests to determine the safety of various types of mine lights in thepresence of inflammable gas, and their accuracy in detecting smallpercentages of mine gas. 

5. --Tests of the various artificial breathing apparatus, and thetraining of miners and of skilled mining engineers in rescue methods. 

The first four of these lines of investigation have to do withpreventive measures, and are those on which ultimately the greatestdependence must be placed. The fifth is one in which the result seems atfirst to be the most apparent. It has to do, not with prevention, butwith the cure of conditions which should not arise, or, at least, shouldbe greatly ameliorated. 

During the last 19 years, 28, 514 men have been killed in the coal-miningindustries. [2] In 1907 alone, 3, 125 men lost their lives in coal mines, and, in addition, nearly 800 were killed in the metal mines and quarriesof the country. Including the injured, 8, 441 men suffered casualties inthe mines in that year. In every mining camp containing 1, 000 men, 4. 86were taken by violent death in that year. In the mining of coal in GreatBritain, 1. 31 men were killed in every 1, 000 employed in the same year;in France, 1. 1; in Belgium, 0. 94, or less than 1 man in every 1, 000employed. It is thus seen that from three to four times as many men arebeing killed in the United States as in any European coal-producingcountry. This safer condition in Europe has resulted from the use ofsafer explosives, or the better use of the explosives available; fromthe reduction in the use of open lights; from the establishment of minerescue stations and the training with artificial breathing apparatus;and from the adoption of regulations for safeguarding the lives of theworkmen. 

The mining engineering field force of the Geological Survey, at the headof which is Mr. George S. Rice, an experienced mining and consultingengineer, has already made great progress in the study of undergroundmining conditions and methods. Nearly all the more dangerous coal minesin the United States have been examined; samples of gas, coal, and dusthave been taken and analyzed at the chemical laboratories at Pittsburg;extended tests have been made as to the explosibility of variousmixtures of gas and air; as to the explosibility of dust from varioustypical coals; as to the chemical composition and physicalcharacteristics of this dust; the degree of fineness necessary to themost explosive conditions; and the methods of dampening the dust bywater, by humidifying, by steam, or of deadening its explosibility bythe addition of calcium chloride, stone dust, etc. A bulletin outliningthe results thus far obtained in the study of the coal-dust problem isnow in course of publication. [3]

After reviewing the history of observations and experiments with coaldust carried on in Europe, and later, the experiments at the French, German, Belgian, and English explosives-testing stations, this bulletintakes up the coal-dust question in the United States. Further chaptersconcern the tests as to the explosibility of coal dust, made by theGeological Survey, at Pittsburg; investigations, both at the Pittsburglaboratory and in mines, as to the humidity of mine air. There is also achapter on the chemical investigations into the ignition of coal dust byDr. J. C. W. Frazer, of the Geological Survey. The application of someof these data to actual mine conditions in Europe, in the last year, istreated by Mr. Axel Larsen; the use of exhaust steam in a mine of theConsolidation Coal Company, in West Virginia, is discussed by Mr. FrankHaas, Consulting Engineer; and the use of sprays in Oklahoma coal minesis the subject of a chapter by Mr. Carl Scholz, Vice-President of theRock Island Coal Mining Company. 

An earlier bulletin setting forth the literature and certain mineinvestigations of explosive gases and dust, [4] has already been issued. After treating of methods of collecting and analyzing the gases found inmines, of investigations as to the rate of liberation of gas from coal, and of studies on coal dust, this bulletin discusses such factors as therestraining influence of shale dust and dampness on coal-dustexplosions. It then takes up practical considerations as to the dangerof explosions, including the relative inflammability of old and freshcoal dust. The problems involved are undergoing further investigationand elaboration, in the light of information already gathered. 

_Permissible Explosives. _--The most important progress in these testsand investigations has been made in those relating to the variousexplosives used in getting coal from mines. Immediately upon theenactment of the first legislation, in the spring of 1908, arrangementswere perfected whereby the lower portion of the old Arsenal groundsbelonging to the War Department and adjacent to the PennsylvaniaRailroad, on the Alleghany River, at 40th and Butler Streets, Pittsburg, Pa. , were transferred to the Interior Department for use in theseinvestigations. Meantime, in anticipation of the appropriation, Mr. Clarence Hall, an engineer experienced in the manufacture and use ofexplosives, was sent to Europe to study the methods of testingexplosives practiced at the Government stations in Great Britain, Germany, Belgium, and France. Mr. Joseph A. Holmes also visited Europefor the purpose of studying methods of ameliorating conditions in themines. Three foreign mining experts, the chiefs of investigating bureausin Belgium, Germany, and England, spent three months studying conditionsin the United States at the invitation of the Secretary of the Interior, to whom they submitted a valuable report. [5]

Under the supervision of the writer, Chief Engineer of theseinvestigations, detailed plans and specifications had been prepared inadvance for the necessary apparatus and the transformation of thebuildings at Pittsburg to the purposes of this work. It was possible, therefore, to undertake immediately the changes in existing buildings, the erection of new buildings, the installation of railway tracks, laboratories, and the plumbing, heating, and lighting plant, etc. Thiswork was carried on with unusual expedition, under the direction of theAssistant Chief Engineer, Mr. James C. Roberts, and was completed withina few months, by which time most of the apparatus was delivered andinstalled. 

One building (No. 17) is devoted to the smaller physical tests ofexplosives. It was rendered fire resistant by heavily covering thefloors, ceiling, and walls with cement on metal lath, and otherwiseprotecting the openings. In it are installed apparatus for determiningcalorific value of explosives, pressure produced on ignition, susceptibility to ignition when dropped, rate of detonation, length andduration of flame, and kindred factors. Elsewhere on the grounds is agallery of boiler-steel plate, 100 ft. Long and more than 6 ft. Indiameter, solidly attached to a mass of concrete at one end, in which isembedded a cannon from which to discharge the explosive under test, andopen at the other end, and otherwise so constructed as to simulate asmall section of a mine gallery (Fig. 2, Plate VI). The heavy mortarpendulum, for the pendulum test for determining the force produced by anexplosive, is near by, as is also an armored pit in which largequantities of explosive may be detonated, with a view to studying theeffects of magazine explosions, and for testing as to the rate at whichignition of an explosive travels from one end to the other of acartridge, and the sensitiveness of one cartridge to explosion bydischarge of another near by. 

 [Illustration: PLATE VI. 

 Fig. 1. --Explosion from Coal Dust in Gas and Dust Gallery No. 1. 

 Fig. 2. --Mine Gallery No. 1. 

 Fig. 3. --Ballistic Pendulum. ]

In another building (No. 21), is a well-equipped chemical laboratory forchemical analyses and investigations of explosives, structuralmaterials, and fuels. 

Several months were required to calibrate the various apparatus, and tomake analyses of the available natural gas to determine the correctmethod of proportioning it with air, so as to produce exact mixtures of2, 4, 6, or 8% of methane with air. Tests of existing explosives weremade in air and in inflammable mixtures of air and gas, with a view tofixing on some standard explosive as a basis of comparison. Ultimately, 40% nitro-glycerine dynamite was adopted as the standard. Investigativetests having been made, and the various factors concerning all theexplosives on the market having been determined, a circular was sent toall manufacturers of explosives in the United States, on January 9th, 1909, and was also published in the various technical journals, throughthe associated press, and otherwise. 

On May 15th, 1909, all the explosives which had been offered for test, as permissible, having been tested, the first list of permissibleexplosives was issued, as given in the following circular:

 “EXPLOSIVES CIRCULAR NO. 1. “DEPARTMENT OF THE INTERIOR. “United States Geological Survey. “May 15, 1909. 

 “LIST OF PERMISSIBLE EXPLOSIVES. “Tested prior to May 15, 1909. 

 “As a part of the investigation of mine explosions authorized by Congress in May, 1908, it was decided by the Secretary of the Interior that a careful examination should be made of the various explosives used in mining operations, with a view to determining the extent to which the use of such explosives might be responsible for the occurrence of these disasters. 

 “The preliminary investigation showed the necessity of subjecting to rigid tests all explosives intended for use in mines where either gas or dry inflammable dust is present in quantity or under conditions which are indicative of danger. 

 “With this in view, a letter was sent by the Director of the United States Geological Survey on January 9, 1909, to the manufacturers of explosives in the United States, setting forth the conditions under which these explosives would be examined and the nature of the tests to which they would be subjected. 

 “Inasmuch as the conditions and tests described in this letter were subsequently followed in testing the explosives given in the list below, they are here reproduced, as follows:

 “(1) The manufacturer is to furnish 100 pounds of each explosive which he desires to have tested; he is to be responsible for the care, handling, and delivery of this material at the testing station on the United States arsenal grounds, Fortieth and Butler streets, Pittsburg, Pa. , at the time the explosive is to be tested; and he is to have a representative present during the tests, who will be responsible for the handling of the packages containing the explosives until they are opened for testing. 

 “(2) No one is to be present at or to participate in these tests except the necessary government officers at the testing station, their assistants, and the representative of the manufacturer of the explosives to be tested. 

 “(3) The tests will be made in the order of the receipt of the applications for them, provided the necessary quantity of the explosive is delivered at the plant by the time assigned, of which due notice will be given by the Geological Survey. 

 “(4) Preference will be given to the testing of explosives that are now being manufactured and that are in that sense already on the market. No test will be made of any new explosive which is not now being manufactured and marketed, until all explosives now on the market that may be offered for testing have been tested. 

 “(5) A list of the explosives which pass certain requirements satisfactorily will be furnished to the state mine inspectors, and will be made public in such further manner as may be considered desirable. 

 “TEST REQUIREMENTS FOR EXPLOSIVES. 

 “The tests will be made by the engineers of the United States Explosives Testing Station at Pittsburg, Pa. , in gas and dust gallery No. 1. The charge of explosive to be fired in tests 1, 2, and 3 shall be equal in disruptive power to one-half pound (227 grams) of 40 per cent. Nitroglycerin dynamite in its original wrapper, of the following formula:

 Nitroglycerin 40 Nitrate of sodium 44 Wood pulp 15 Calcium carbonate 1 --- 100

 “Each charge shall be fired with an electric fuse of sufficient power to completely detonate or explode the charge, as recommended by the manufacturer. The explosive must be in such condition that the chemical and physical tests do not show any unfavorable results. The explosives in which the charge used is less than 100 grams (0. 22 pound) will be weighed in tinfoil without the original wrapper. 

 “The dust used in tests 2, 3, and 4 will be of the same degree of fineness and taken from one mine. [6]

 [Footnote 6: With a view to obtaining a dust of uniform purity and inflammability. ]

 “TEST 1. --Ten shots with the charge as described above, in its original wrapper, shall be fired, each with 1 pound of clay tamping, at a gallery temperature of 77° F. , into a mixture of gas and air containing 8 per cent. Of methane and ethane. An explosive will pass this test if all ten shots fail to ignite the mixture. 

 “TEST 2. --Ten shots with charge as previously noted, in its original wrapper, shall be fired, each with 1 pound of clay tamping at a gallery temperature of 77° F. , into a mixture of gas and air containing 4 per cent. Of methane and ethane and 20 pounds of bituminous coal dust, 18 pounds of which is to be placed on shelves laterally arranged along the first 20 feet of the gallery, and 2 pounds to be placed near the inlet of the mixing system in such a manner that all or part of it will be suspended in the first division of the gallery. An explosive will pass this test if all ten shots fail to ignite the mixture. 

 “TEST 3. --Ten shots with charge as previously noted, in its original wrapper, shall be fired, each with 1 pound of clay tamping at a gallery temperature of 77° F. , into 40 pounds of bituminous coal dust, 20 pounds of which is to be distributed uniformly on a horse placed in front of the cannon and 20 pounds placed on side shelves in sections 4, 5, and 6. An explosive will pass this test if all ten shots fail to ignite the mixture. 

 “TEST 4. --A limit charge will be determined within 25 grams by firing charges in their original wrappers, untamped, at a gallery temperature of 77° F. , into a mixture of gas and air containing 4 per cent. Of methane and ethane and 20 pounds of bituminous coal dust, to be arranged in the same manner as in test 2. This limit charge is to be repeated five times under the same conditions before being established. 

 “NOTE. --At least 2 pounds of clay tamping will be used with slow-burning explosives. 

 “Washington, D. C. , _January 9, 1909_. 

 “In response to the above communication applications were received from 12 manufacturers for the testing of 29 explosives. Of these explosives, the 17 given in the following list have passed all the test requirements set forth, and will be termed permissible explosives. 

 “_Permissible explosives tested prior to May 15, 1909. _

 ----------------------------+---------------------------------------- Brand. | Manufacturer. ----------------------------+---------------------------------------- Ætna coal powder A | Ætna Powder Co. , Chicago, Ill. Ætna coal powder B | Do. Carbonite No. 1 | E. I. Dupont de Nemours Powder Co. , | Wilmington, Del. Carbonite No. 2 | E. I. Du Pont de Nemours Powder Co. , | Wilmington, Del. Carbonite No. 3 | Do. Carbonite No. 1 L. F. | Do. Carbonite No. 2 L. F. | Do. Coal special No. 1 | Keystone Powder Co. , Emporium, Pa. Coal special No. 2 | Do. Coalite No. 1 | Potts Powder Co. , New York City. Coalite No. 2 D | Do. Collier dynamite No. 2 | Sinnamahoning Powder Co. , Emporium, Pa. Collier dynamite No. 4 | Do. Collier dynamite No. 5 | Do. Masurite M. L. F. | Masurite Explosive Co. , Sharon, Pa. Meteor dynamite | E. I. Du Pont de Nemours Powder Co. , | Wilmington, Del. Monobel | Do. ----------------------------+----------------------------------------

 “Subject to the conditions named below, a permissible explosive is defined as an explosive which has passed gas and dust gallery tests Nos. 1, 2, and 3 as described above, and of which in test No. 4 1½ pounds (680 grams) of the explosive has been fired into the mixture there described without causing an ignition. 

 “_Provided:_

 “1. That the explosive is in all respects similar to the sample submitted by the manufacturer for test. 

 “2. That double-strength detonators are used of not less strength than 1 gram charge consisting by weight of 90 parts of mercury fulminate and 10 parts of potassium chlorate (or its equivalent), except for the explosive ‘Masurite M. L. F. ’ for which the detonator shall be of not less strength than 1½ grams charge. 

 “3. That the explosive, if in a frozen condition, shall be thoroughly thawed in a safe and suitable manner before use. 

 “4. That the amount used in practice does not exceed 1½ pounds (680 grams) properly tamped. 

 “The above partial list includes the permissible explosives that have passed these tests prior to May 15, 1909. The announcement of the passing of like tests by other explosives will be made public immediately after the completion of the tests for such explosives. 

 “A description of the method followed in making these and the many additional tests to which each explosive is subjected, together with the full data obtained in each case, will be published by the Survey at an early date. 

 “NOTES AND SUGGESTIONS. 

 “It may be wise to point out in this connection certain differences between the permissible explosives as a class and the black powders now so generally used in coal mining, as follows:

 “(_a_) With equal quantities of each, the flame of the black powder is more than three times as long and has a duration three thousand to more than four thousand times that of one of the permissible explosives, also the rate of explosion is slower. 

 “(_b_) The permissible explosives are one and one-fourth to one and three-fourths times as strong and are said, if properly used, to do twice the work of black powder in bringing down coal; hence only half the quantity need be used. 

 “(_c_) With 1 pound of a permissible explosive or 2 pounds of black powder, the quantity of noxious gases given off from a shot averages approximately the same, the quantity from the black powder being less than from some of the permissible explosives and slightly greater than from others. The time elapsing after firing before the miner returns to the working face or fires another shot should not be less for permissible explosives than for black powder. 

 “The use of permissible explosives should be considered as supplemental to and not as a substitute for other safety precautions in mines where gas or inflammable coal dust is present under conditions indicative of danger. As stated above, they should be used with strong detonators; and the charge used in practice should not exceed 1½ pounds, and in many cases need not exceed 1 pound. 

 “Inasmuch as no explosive manufactured for use in mining is flameless, and as no such explosive is entirely safe under all the variable mining conditions, the use of the terms ‘flameless’ and ‘safety’ as applied to explosives is likely to be misunderstood, may endanger human life, and should be discouraged. 

 “JOSEPH A. HOLMES, “_Expert in Charge Technologic Branch_. 

 “Approved, May 18, 1909: “GEO. OTIS SMITH, “_Director_. ”

In the meantime, many of the explosives submitted, which heretofore hadbeen on the market as safety explosives, were found to be unsafe foruse in gaseous or dusty mines, and the manufacturers were permittedto withdraw them. Their weaknesses being known, as a result of thesetests, the manufacturers were enabled to produce similar, but safer, explosives. Consequently, applications for further tests continuedto pour in, as they still do, and on October 1st, 1909, a second listof permissible explosives was issued, as follows:

 “EXPLOSIVES CIRCULAR NO. 2. “DEPARTMENT OF THE INTERIOR. “United States Geological Survey. “October 1, 1909. 

 “LIST OF PERMISSIBLE EXPLOSIVES. “Tested prior to October 1, 1909. 

 “The following list of permissible explosives tested by the United States Geological Survey at Pittsburg, Pa. , is hereby published for the benefit of operators, mine owners, mine inspectors, miners, and others interested. 

 “The conditions and test requirements described in Explosives Circular No. 1, issued under date of May 15, 1909, have been followed in all subsequent tests. 

 “Subject to the provisions named below, a permissible explosive is defined as an explosive which is in such condition that the chemical and physical tests do not show any unfavorable results; which has passed gas and dust gallery tests Nos. 1 and 3, as described in circular No. 1; and of which, in test No. 4, 1½ pounds (680 grams) has been fired into the mixture there described without causing ignition. 

 “_Permissible explosives tested prior to October 1, 1909. _

 “[Those reported in Explosives Circular No. 1 are marked *. ]

 ------------------------------+------------------------------------- Brand. | Manufacturer. ------------------------------+------------------------------------- *Ætna coal powder A | Ætna Powder Co. , Chicago, Ill. Ætna coal powder AA | Do. *Ætna coal powder B | Do. Ætna coal powder C | Do. Bituminite No. 1 | Jefferson Powder Co. , Birmingham, | Ala. Black Diamond No. 3 | Illinois Powder Manufacturing Co. , | St. Louis, Mo. Black Diamond No. 4 | Do. *Carbonite No. 1 | E. I. Du Pont de Nemours Powder Co. , | Wilmington, Del. *Carbonite No. 2 | Do. *Carbonite No. 3 | Do. *Carbonite No. 1-L. F. | Do. *Carbonite No. 2-L. F. | Do. *Coalite No. 1 | Potts Powder Co. , New York City. *Coalite No. 2-D. | Do. *Coal special No. 1 | Keystone Powder Co. , Emporium, Pa. *Coal special No. 2 | Do. *Collier dynamite No. 2. | Sinnamahoning Powder Manufacturing | Co. , Emporium, Pa. *Collier dynamite No. 4. | Do. *Collier dynamite No. 5. | Do. Giant A low-flame dynamite. | Giant Powder Co. (Con. ), Giant, Cal. Giant B low-flame dynamite. | Do. Giant C low-flame dynamite. | Do. *Masurite M. L. F. | Masurite Explosives Co. , Sharon, Pa. *Meteor dynamite. | E. I. Du Pont de Nemours Powder Co. , | Wilmington, Del. Mine-ite A. | Burton Powder Co. , Pittsburg, Pa. Mine-ite B. | Do. *Monobel. | E. I. Du Pont de Nemours Powder Co. , | Wilmington, Del. Tunnelite No. 5. | G. R. McAbee Powder and Oil Co. , | Pittsburg, Pa. Tunnelite No. 6. | Do. Tunnelite No. 7. | Do. Tunnelite No. 8. | Do. ------------------------------+-------------------------------------

 “_Provided:_

 “1. That the explosive is in all respects similar to sample submitted by the manufacturer for test. 

 “2. That No. 6 detonators, preferably No. 6 electric detonators (double strength), are used of not less strength than 1 gram charge, consisting by weight of 90 parts of mercury fulminate and 10 parts of potassium chlorate (or its equivalent), except for the explosive ’Masurite M. L. F. , ’ for which the detonator shall be of not less strength than 1½ grams charge. 

 “3. That the explosive, if frozen, shall be thoroughly thawed in a safe and suitable manner before use. 

 “4. That the amount used in practice does not exceed 1½ pounds (680 grams), properly tamped. 

 “The above partial list includes all the permissible explosives that have passed these tests prior to October 1, 1909. The announcement of the passing of like tests by other explosives will be made public immediately after the completion of the tests. 

 “With a view to the wise use of these explosives it may be well in this connection to point out again certain differences between the permissible explosives as a class and the black powders now so generally used in coal mining, as follows:

 “(_a_) With equal quantities of each, the flame of the black powder is more than three times as long and has a duration three thousand to more than four thousand times that of one of the permissible explosives; the rate of explosion also is slower. 

 “(_b_) The permissible explosives are one and one-fourth to one and three-fourths times as strong and are said, if properly used, to do twice the work of black powder in bringing down coal; hence only half the quantity need be used. 

 “(_c_) With 1 pound of a permissible explosive or 2 pounds of black powder, the quantity of noxious gases given off from a shot averages approximately the same, the quantity from the black powder being less than from some of the permissible explosives and slightly greater than from others. The time elapsing after firing before the miner returns to the working face or fires another shot should not be less for permissible explosives than for black powder. 

 “The use of permissible explosives should be considered as supplemental to and not as a substitute for other safety precautions in mines where gas or inflammable coal dust is present under conditions indicating danger. As stated above, they should be used with strong detonators, and the charge used in practice should not exceed 1½ pounds and in many cases need not exceed 1 pound. 

 “JOSEPH A. HOLMES, “_Expert in Charge Technologic Branch. _ “Approved, October 11, 1909. “H. C. RIZER, “_Acting Director. _”

The second list contains 31 explosives which the Government is preparedto brand as permissible, and therefore comparatively safe, for use ingaseous and dusty mines. An equally large number of so-called safetypowders failed to pass these tests. Immediately on the passing of thetests, as to the permissibility of any explosive, the facts are reportedto the manufacturer and to the various State mine inspectors. Whenpublished, the permissible lists were issued to all explosivesmanufacturers, all mine operators in the United States, and Stateinspectors. The effect has been the enactment, by three of the largestcoal-producing States, of legislation or regulations prohibiting the useof any but permissible explosives in gaseous or dusty mines, and otherStates must soon follow. To prevent fraud, endeavor is being made torestrict the use of the brand “Permissible Explosive, U. S. TestingStation, Pittsburg, Pa. , ” to only such boxes or packages as containlisted permissible explosives. 

As these tests clearly demonstrate, both in the records thereof andvisually to such as follow them, that certain explosives, especiallythose which are slow-burning like black powder, or produce hightemperature in connection with comparative slow burning, will ignitemixtures of gas and air, or mixtures of coal dust and air, and causeexplosions. The results point out clearly to all concerned, the dangerof using such explosives. The remedy is also made available by theannouncement of the names of a large number of explosives now on themarket at reasonable cost, which will not cause explosions under theseconditions. It is believed that when permissible explosives aregenerally adopted in coal mines, this source of danger will have beengreatly minimized. 

_Explosives Investigations. _--Questions have arisen on the part ofminers or of mine operators as to the greater cost in using permissibleexplosives due to their expense, which is slightly in excess of that ofother explosives; as to their greater shattering effect in breaking downthe coal, and in giving a smaller percentage of lump and a largerpercentage of slack; and as to the possible danger of breathing thegases produced. 

Observations made in mines by Mr. J. J. Rutledge, an experienced coalminer and careful mining engineer connected with the Geological Survey, as to the amount of coal obtained by the use of permissible and otherexplosives, tend to indicate that the permissible explosives are notmore, but perhaps less expensive than others, in view of the fact that, because of their greater relative power, a smaller quantity is requiredto do the work than is the case, say, with black powder. On the otherhand, for safety and for certainty of detonation, stronger detonatorsare recommended for use with permissible explosives, preferably electricdetonators. These may cost a few cents more per blast than the squib orfuse, but there is no danger that they will ignite the gas, and thedifference in cost is, in some measure, offset by the greater certaintyof action and the fact that they produce a much more powerful explosion, thus again permitting the use of still smaller quantities of theexplosive and, consequently, reducing the cost. These investigations arestill in progress. 

Concerning the shattering of the coal: This is being remedied in some ofthe permissible explosives by the introduction of dopes, moisture, orother means of slowing down the disruptive effect, so as to produce theheaving and breaking effect obtained with the slower-burning powdersinstead of the shattering effect produced by dynamite. There is everyreason to believe that as the permissible explosives are perfected, andas experience develops the proper methods of using them, this difficultywill be overcome in large measure. This matter is also beinginvestigated by the Survey mining engineers and others, by the actualuse of such explosives in coal-mining operations. 

Of the gases given off by explosives, those resulting from black powderare accompanied by considerable odor and smoke, and, consequently, theminers go back more slowly after the shots, allowing time for the gasesto be dissipated by the ventilation. With the permissible explosive, theminer, seeing no smoke and observing little odor, is apt to beincautious, and to think that he may run back immediately. As more islearned of the use of these explosives, this source of danger, which is, however, inconsiderable, will be diminished. Table 1 gives thepercentages of the gaseous products of combustions from equal weights ofblack powder and two of the permissible explosives. Of the latter, onerepresents the maximum amount of injurious gases, and the other theminimum amount, between which limits the permissible explosivesapproximately vary. 

Such noxious gases as may be produced by the discharge of the explosiveare diluted by a much larger volume of air, and are practicallyharmless, as proven by actual analysis of samples taken at the faceimmediately after a discharge. 

 TABLE 1. 

 --------+---------+-------------------------- | | Permissible Explosives. | Black |-------------+------------ | powder. | Maximum. | Minimum. --------+---------+-------------+------------ CO_{2} | 22. 8 | 14. 50 | 21. 4 CO | 10. 3 | 27. 74 | 1. 3 N | 10. 3 | 45. 09 | 74. 4 --------+---------+-------------+------------

In addition to investigations as to explosives for use in coal mining, the Explosives Section of the Geological Survey analyzes and tests allsuch materials, fuses, caps, etc. , purchased by the Isthmian CanalCommission, as well as many other kinds used by the Government. It isthus acquiring a large fund of useful information, which will bepublished from time to time, relative to the kinds of explosives and themanner of using them best suited to any blasting operations, eitherabove or under water, in hard rock, earth, or coal. There has beenissued from the press, recently, a primer of explosives, [7] by Mr. Clarence Hall, the engineer in charge of these tests, and Professor C. E. Munroe, Consulting Explosives Chemist, which contains a large amountof valuable fundamental information, so simply expressed as to be easilyunderstandable by coal miners, and yet sufficiently detailed to be avaluable guide to all persons who have to handle or use explosives. 

In the first chapters are described the various combustible substances, and the chemical reactions leading to their explosibility. The low andhigh explosives are differentiated, and the sensitiveness of fulminateof mercury and other detonators is clearly pointed out. The variousexplosives, such as gunpowder, black blasting powder, potassium chloratepowders, nitro-glycerine powders, etc. , are described, and theirpeculiarities and suitability for different purposes are set forth. Thecharacter and method of using the different explosives, both in openingup work and in enclosed work in coal mines, follow, with information asto the proper method of handling, transporting, storing, and thawing thesame. Then follow chapters on squibs, fuses, and detonators; on methodsof shooting coal off the solid; location of bore-holes; undercutting;and the relative advantages of small and large charges, withdescriptions of proper methods of loading and firing the same. Thesubjects of explosives for blasting in rock, firing machines, blastingmachines, and tests thereof, conclude the report. 

The work of the chemical laboratory in which explosives are analyzed, and in which mine gases and the gases produced by combustion ofexplosives and explosions of coal-gas or coal dust are studied, has beenof the most fundamental and important character. The Government isprocuring a confidential record of the chemical composition and mode ofmanufacture of all explosives, fuses, etc. , which are on the market. This information cannot but add greatly to the knowledge as to thechemistry of explosives for use in mines, and will furnish the basis onwhich remedial measures may be devised. 

A bulletin (shortly to go to press) which gives the details of thephysical tests of the permissible explosives thus far tested, will setforth elaborately the character of the testing apparatus, and the methodof use and of computing results. [8]

This bulletin contains a chapter, by Mr. Rutledge, setting forth indetail the results of his observations as to the best methods of usingpermissible explosives in getting coal from various mines in which theyare used. This information will be most valuable in guiding miningengineers who desire to adopt the use of permissible explosives, as tothe best methods of handling them. 

_Electricity in Mines. _--In connection with the use of electricity inmines, an informal series of tests has been made on all enclosedelectric fuses, as to whether or not they will ignite an explosivemixture of air and gas when blown out. The results of this work, whichis under the direction of Mr. H. H. Clark, Electrical Engineer forMines, have been furnished the manufacturers for their guidance inperfecting safer fuses, a series of tests of which has been announced. Aseries of tests as to the ability of the insulation of electric wiringto withstand the attacks of acid mine waters is in progress, which willlead, it is hoped, to the development of more permanent and cheaperinsulation for use in mine wiring. A series of competitive tests ofenclosed motors for use in mines has been announced, and is in progress, the object being to determine whether or not sparking from such motorswill cause an explosion in the presence of inflammable gas. 

In the grounds outside of Building No. 10 is a large steel gallery, muchshorter than Gallery No. 1, in fact, but 30 ft. In length, and muchgreater in diameter, namely, 10 ft. (Fig. 3, Plate X), in which electricmotors, electric cutting machines, and similar apparatus, are beingtested in the presence of explosive mixtures of gas and dust and withlarge amperage and high voltage, such as may be used in the largestelectrical equipment in mines. 

The investigation as to the ability of insulation to withstand theeffects of acid mine waters has been very difficult and complicated. Atfirst it was believed possible that mine waters from nearby Pennsylvaniamines and of known percentages of acidity could be procured and kept inan immersion tank at approximately any given percentage of strength. This was found to be impracticable, as these waters seem to undergorapid change the moment they are exposed to the air or are transported, in addition to the changes wrought by evaporation in the tank. It hasbeen necessary, therefore, to analyze and study carefully these waterswith a view to reproducing them artificially for the purpose of thesetests. Concerning the insulation, delicate questions have arisen as to astandard of durability which shall be commensurate with reasonable cost. These preliminary points are being solved in conference with themanufacturers, and it is expected that the results will soon permit ofstarting the actual tests. 

_Safety-Lamp Investigations. _--Many so-called safety lamps are on themarket, and preliminary tests of them have been made in the lampgallery, in Building No. 17 (Fig. 2, Plate X). After nearly a year ofendeavor to calibrate this gallery, and to co-ordinate its results withthose produced in similar galleries in Europe, this preliminary inquiryhas been completed, and the manufacturers and agents of all safety lampshave been invited to be present at tests of their products at thePittsburg laboratory. 

A circular dated November 19th, 1909, contains an outline of thesetests, which are to be conducted under the direction of Mr. J. W. Paul, an experienced coal-mining engineer and ex-Chief of the Department ofState Mine Inspection of West Virginia. The lamps will be subjected tothe following tests:

(_a_). --Each lamp will be placed in a mixture of air and explosivenatural gas containing 6, 8, and 10% of gas, moving at a velocity offrom 200 to 2, 500 ft. Per min. , to determine the velocity of the aircurrent which will ignite the mixture surrounding the lamp. The currentwill be made to move against the lamp in a horizontal, verticalascending, and vertical descending direction, and at an angle of 45°, ascending and descending. 

(_b_). --After completing the tests herein described, the lamps will besubjected to the tests described under (_a_), with the air and gasmixture under pressure up to 6 in. Of water column. 

(_c_). --Under the conditions outlined in (_a_), coal dust will beintroduced into the current of air and gas to determine its effect, ifany, in inducing the ignition of the gas mixture. 

(_d_). --Each lamp will be placed in a mixture of air and varyingpercentages of explosive natural gas to determine the action of the gason the flame of the lamp. 

(_e_). --Each lamp will be placed in a mixture of air and varyingpercentages of carbonic acid gas to determine the action of the gas onthe flame. 

(_f_). --Lamps equipped with internal igniters will be placed inexplosive mixtures of air and gas in a quiet state and in a movingcurrent, and the effect of the igniter on the surrounding mixture willbe observed. 

(_g_). --The oils (illuminants) used in the lamps will be tested as toviscosity, gravity, flashing point, congealing point, and composition. 

(_h_). --Safety-lamp globes will be tested by placing each globe inposition in the lamp and allowing the flame to impinge against the globefor 3 min. After the lamp has been burning with a full flame for 10min. , to determine whether the globe will break. 

(_i_). --Each safety-lamp globe will be mounted in a lighted lamp withup-feed, and placed for 5 min. In an explosive mixture of air and gasmoving at the rate of 1, 000 ft. Per min. , to determine whether the heatwill break the glass and, if it is broken, to note the character of thefracture. 

(_j_). --Safety-lamp globes will be broken by impact, by allowing eachglobe to fall and strike, horizontally, on a block of seasoned whiteoak, the distance of fall being recorded. 

(_k_). --Each safety lamp globe will be mounted in a safety lamp and, when the lamp is in a horizontal position, a steel pick weighing 100grammes will be permitted to fall a sufficient distance to break theglobe by striking its center, the distance of the fall to be recorded. 

(_l_). --To determine the candle power of safety lamps, a photometerequipped with a standardized lamp will be used. The candle-power will bedetermined along a line at right angles to the axis of the flame; alsoalong lines at angles to the axis of the flame both above and below thehorizontal. The candle-power will be read after the lamp has beenburning 20 min. 

(_m_). --The time a safety lamp will continue to burn with a full chargeof illuminant will be determined. 

(_n_). --Wicks in lamps must be of sufficient length to be at all timesin contact with the bottom of the vessel in which the illuminant iscontained, and, before it is used, the wick shall be dried to removemoisture. 

_Mine-Rescue Methods. _--Mr. Paul, who has had perhaps as wide anexperience as any mining man in the investigation of and in rescue workat mine disasters, is also in charge of the mine-rescue apparatus andtraining for the Geological Survey. These operations consist chiefly ofa thorough test of the various artificial breathing apparatus, orso-called oxygen helmets. Most of these are of European make and findfavor in Great Britain, Belgium, France, or Germany, largely accordingas they are of domestic design and manufacture. As yet nothing has beenproduced in the United States which fulfills all the requirements of athoroughly efficient and safe breathing apparatus for use in minedisasters. 

At the Pittsburg testing station there are a number of all kinds ofapparatus. The tests of these are to determine ease of use, of repair, durability, safety under all conditions, period during which the supplyof artificial air or oxygen can be relied on, and other essential data. 

In addition to the central testing station, sub-stations for trainingminers, and as headquarters for field investigation as to the causes ofmine disasters and for rescue work in the more dangerous coal fields, have been established; at Urbana, Ill. , in charge of Mr. R. Y. Williams, Mining Engineer; at Knoxville, Tenn. , in charge of Mr. J. J. Rutledge, Mining Engineer; at McAlester, Okla. , in charge of Mr. L. M. Jones, Assistant Mining Engineer; and at Seattle, Wash. , in charge of Mr. HughWolflin, Assistant Mining Engineer. Others may soon be established inColorado and elsewhere, in charge of skilled mining engineers who havebeen trained in this work at Pittsburg, and who will be assisted bytrained miners. It is not to be expected that under any butextraordinary circumstances, such as those which occurred at Cherry, Ill. , the few Government engineers, located at widely scattered pointsthroughout the United States, can hope to save the lives of miners aftera disaster occurs. As a rule, all who are alive in the mine on such anoccasion, are killed within a few hours. This is almost invariably thecase after a dust explosion, and is likely to be true after a gasexplosion, although a fire such as that at Cherry, Ill. , offers thegreatest opportunity for subsequent successful rescue operations. Themost to be hoped for from the Government engineers is that they shalltrain miners and be available to assist and advise State inspectors andmine owners, should their services be called for. 

It should be borne in mind that the Federal Government has no policeduties in the States, and that, therefore, its employees may not directoperations or have other responsible charge in the enforcement of Statelaws. There is little reason to doubt that these Federal miningengineers, both because of their preliminary education as miningengineers and their subsequent training in charge of mine operations, and more recently in mine-accidents investigations and rescue work, areeminently fitted to furnish advice and assistance on such occasions. Themere fact that, within a year, some of these men have been present at, and assisted in, rescue work or in opening up after disasters at nearlytwenty of such catastrophes, whereas the average mining engineer orsuperintendent may be connected with but one in a lifetime, should maketheir advice and assistance of supreme value on such occasions. Theycannot be held in any way responsible for tardiness, however, nor beunduly credited with effective measures taken after a mine disaster, because of their lack of responsible authority or charge, except inoccasional instances where such may be given them by the mine owners orthe State officials, from a reliance on their superior equipment forsuch work. 

Successful rescue operations may only be looked for when the time, nowbelieved to be not far distant, has been reached when the mine operatorsthroughout the various fields will have their own rescue stations, as isthe practice in Europe, and have available, at certain strategic mines, the necessary artificial breathing apparatus, and have in their employskilled miners who have been trained in rescue work at the Governmentstations. Then, on the occurrence of a disaster, the engineer in chargeof the Government station may advise by wire all those who have properequipment or training to assemble, and it may be possible to gather, within an hour or two of a disaster, a sufficiently large corps ofhelmet-men to enable them to recover such persons as have not beenkilled before the fire--which usually is started by the explosion--hasgained sufficient headway to prevent entrance into the mine. Withoutsuch apparatus, it is essential that the fans be started, and the minecleared of gas. The usual effect of this is to give life to anyincipient fire. With the apparatus, the more dense the gas, the saferthe helmet-men are from a secondary explosion or from the rapid ignitionof a fire, because of the absence of the oxygen necessary to combustion. 

The miners who were saved at Cherry, Ill. , on November 20th, 1909, owetheir lives primarily to the work of the Government engineers. Thesub-station of the Survey at Urbana, Ill. , was promptly notified of thedisaster on the afternoon of November 13th. Arrangements wereimmediately made, whereby Mr. R. Y. Williams, Mining Engineer in Charge, and his Assistant, Mr. J. M. Webb, with their apparatus, were rushed byspecial train to the scene, arriving early the following day (Sunday). 

Chief Mining Engineer, George S. Rice, Chief of Rescue Division, J. W. Paul, and Assistant Engineer, F. F. Morris, learned of the disasterthrough the daily press, at their homes in Pittsburg, on Sunday. Theyleft immediately with four sets of rescue apparatus, reaching Cherry onMonday morning. Meantime, Messrs. Williams and Webb, equipped withoxygen helmets, had made two trips into the shaft, but were driven outby the heat. Both shafts were shortly resealed with a view to combatingthe fire, which had now made considerable headway. 

The direction of the operations at Cherry, was, by right ofjurisdiction, in charge of the State Mine Inspectors of Illinois, atwhose solicitation the Government engineers were brought into conferenceas to the proper means to follow in an effort to get into the mine. Thedisaster was not due to an explosion of coal or gas, but was the resultof a fire ignited in hay, in the stable within the mine. The flame hadcome through the top of the air-shaft, and had disabled the ventilatingfans. A rescue corps of twelve men, unprotected by artificial breathingapparatus, had entered the mine, and all had been killed. When theshafts were resealed on Monday evening, the 15th, a small hole was leftfor the insertion of a water-pipe or hose. During the afternoon andevening, a sprinkler was rigged up, and, by Tuesday morning, was insuccessful operation, the temperature in the shaft at that time being109° Fahr. After the temperature had been reduced to about 100°, theFederal engineers volunteered to descend into the shaft and make anexploration. The rescue party, consisting of Messrs. Rice, Paul, andWilliams, equipped with artificial breathing apparatus, made anexploration near the bottom of the air-shaft and located the first body. After they had returned to the surface, three of the Illinois StateInspectors, who had previously received training by the Governmentengineers in the use of the rescue apparatus, including Inspectors Mosesand Taylor, descended, made tests of the air, and found that with thefan running slowly, it was possible to work in the shaft. The rescuecorps then took hose down the main shaft, having first attached it to afire engine belonging to the Chicago Fire Department. Water was directedon the fire at the bottom of the shaft, greatly diminishing its force, and it was soon subdued sufficiently to permit the firemen to enter themine without the protection of breathing apparatus. 

Unfortunately, these operations could be pursued only under the mostdisadvantageous circumstances and surrounded by the greatest possibleprecautions, due to the frequent heavy falls of roof--a result of theheating by the mine fire--and the presence of large quantities ofblack-damp. All movements of unprotected rescuers had to be preceded byexploration by the trained rescue corps, who analyzed the gases, as thefire still continued to burn, and watched closely for falls, possibleexplosions, or a revival of the fire. While the heavy work of shoringup, and removing bodies, was being carried on by the unprotected rescueforce, the helmet-men explored the more distant parts of the mine, andon Saturday afternoon, November 20th, one week after the disaster, aroom was discovered in which a number of miners, with great presence ofmind, had walled themselves in in order to keep out the smoke and heat. From this room 20 living men were taken, of whom 12 were recovered in ahelpless condition, by the helmet-men. 

This is not the first time this Government mining corps has performedvaliant services. Directly and indirectly the members have saved fromfifteen to twenty lives in the short time they have been organized. Atthe Marianna, Pa. , disaster, the corps found one man still alive among150 bodies, and he was brought to the surface. He recovered entirelyafter a month in the hospital. 

At the Leiter mine, at Zeigler, Ill. , two employees, who had beentrained in the use of the oxygen helmets by members of the Government’scorps, went down into the mine, following an explosion, and brought oneman to the surface, where they resuscitated him. 

Equally good service, either in actual rescue operations, or inexplorations after mine disasters, or in fire-fighting, has beenrendered by this force at the Darr, Star Junction, Hazel, Clarinda, Sewickley, Berwind-White No. 37, and Wehrum, Pa. , mine disasters; atMonongah and Lick Branch, W. Va. ; at Deering, Sunnyside, and Shelburn, Ind. , Jobs, Ohio, and at Roslyn, Wash. 

_Explosives Laboratory. _--The rooms grouped at the south end of BuildingNo. 21, at Pittsburg, are occupied as a laboratory for the chemicalexamination and analysis of explosives, and are in charge of Mr. W. O. Snelling. 

Samples of all explosives used in the testing gallery, ballisticpendulum, pressure gauge, and other testing apparatus, are heresubjected to chemical analysis in order to determine the componentmaterials and their exact percentages. Tests are also made to determinethe stability of the explosive, or its liability to decompose at varioustemperatures, and other properties which are of importance in showingthe factors which will control the safety of the explosive duringtransportation and storage. 

In the investigation of all explosives, the first procedure is aqualitative examination to determine what constituents are present. Owing to the large number of organic and inorganic compounds which enterinto the composition of explosive mixtures, this examination must bethorough. Several hundred chemical bodies have been used in explosivesat different times, and some of these materials can be separated fromothers with which they are mixed only by the most careful and exactmethods of chemical analysis. 

Following the qualitative examination, a method is selected for theseparation and weighing of each of the constituents previously found tobe present. These methods, of course, vary widely, according to theparticular materials to be separated, it being usually necessary todevise a special method of analysis for each explosive, unless it isfound, by the qualitative analysis, to be similar to some ordinaryexplosive, in which case the ordinary method of analysis of thatexplosive can be carried out. Most safety powders require specialtreatment, while most grades of dynamite and all ordinary forms of blackblasting powder are readily analyzed by the usual methods. 

The examination of black blasting powder has been greatly facilitatedand, at the same time, made considerably more accurate, by means of adensimeter devised at this laboratory. In this apparatus a Torricellianvacuum is used as a means of displacing the air surrounding the grainsof powder, and through very simple manipulation the true density ofblack powder is determined with a high degree of accuracy. In BuildingNo. 17 there is an apparatus for separating or grading the sizes ofblack powder (Fig. 1, Plate X). 

By means of two factors, the moisture coefficient and the hygroscopiccoefficient, which have been worked out at this laboratory, a number ofimportant observations can be made on black powder, in determining therelative efficiency of the graphite coating to resist moisture, and alsoas a means of judging the thoroughness with which the components of thepowder are mixed. The moisture coefficient relates to the amount ofmoisture which is taken up by the grains of the powder in a definitetime under standard conditions of saturation; and the hygroscopiccoefficient relates to the affinity of the constituents of the powderfor moisture under the same standard conditions. 

Besides the examination of explosives used at the testing station, thosefor the Reclamation Service, the Isthmian Canal Commission, and otherdivisions of the Government, are also inspected and analyzed at theexplosives laboratory. At the present time, the Isthmian CanalCommission is probably the largest user of explosives in the world, andsamples used in its work are inspected, tested, and analyzed at thislaboratory, and at the branch laboratories at Gibbstown and PomptonLakes, N. J. , and at Xenia, Ohio. 

Aside from the usual analysis of explosives for the Isthmian CanalCommission, special tests are made to determine the liability of theexplosive to exude nitro-glycerine, and to deteriorate in unfavorableweather conditions. These tests are necessary, because of the warm andmoist climate of the Isthmus of Panama. 

_Gas and Dust Gallery No. 1. _--Gallery No. 1 is cylindrical in form, 100 ft. Long, and has a minimum internal diameter of 6⅓ ft. It consistsof fifteen similar sections, each 6⅔ ft. Long and built up in in-and-outcourses. The first three sections, those nearest the concrete head, areof ½-in. Boiler-plate steel, the remaining twelve sections are of ⅜-in. Boiler-plate steel, and have a tensile strength of, at least, 55, 000 lb. Per sq. In. Each section has one release pressure door, centrally placedon top, equipped with a rubber bumper to prevent its destruction whenopened quickly. In use, this door may be either closed and unfastened, closed and fastened by stud-bolts, or left open. Each section is alsoequipped with one ¾-in. Plate-glass window, 6 by 6 in. , centrally placedin the side of the gallery (Fig. 1, and Figs. 1 and 2, Plate VI). Thesections are held together by a lap-joint. At each lap-joint there is, on the interior of the gallery, a 2½-in. Circular, angle iron, on theface of which a paper diaphragm may be placed and held in position bysemicircular washers, studs, and wedges. These paper diaphragms are usedto assist in confining a gas-and-air mixture. 

 [Illustration: Fig. 1. 

 EXPLOSIVES TESTING GALLERY No. 1]

Natural gas from the mains of the City of Pittsburg is used to representthat found in the mines by actual analysis. A typical analysis of thisgas is as follows:

Volumetric Analysis of Typical Natural Gas. 

 Hydrogen gases 0 Carbon dioxide 0. 1 Oxygen 0 Heavy hydrocarbons 0 Carbon monoxide 0 Methane 81. 8 Ethane 16. 8 Nitrogen 1. 3

The volume of gas used is measured by an accurate test meter reading toone-twentieth of a cubic foot. The required amount is admitted near thebottom, to one or more of the 20-ft. Divisions of the gallery, from a2-in. Pipe, 14 ft. Long. The pipe has perforations arranged so that anequal flow of gas is maintained from each unit length. 

Each 20-ft. Division of the gallery is further equipped with an exteriorcirculating system, as shown by Fig. 1, thus providing an efficientmethod of mixing the gas with the air. For the first division thiscirculating system is stationary, a portion of the piping being equippedwith heating coils for maintaining a constant temperature. 

The other divisions have a common circulating system mounted on a truckwhich may be used on any of these divisions. Valves are provided forisolating the fan so that a possible explosion will not injure it. 

In the center section of each division is an indicator cock which isused to provide means of recording pressures above and belowatmospheric, or of sampling the air-and-gas mixture. The first divisionof the gallery is equipped with shelves laterally placed, for thesupport of coal dust. 

The cannon in which the explosive is fired is placed in the concretehead, the axial line of the bore-hole being coincident with that of thegallery. This cannon (Fig. 2) is similar to that used in the ballisticpendulum. The charge is fired electrically from the observation room. Tominimize the risk of loading the cannon, the charger carries in hispocket the plug of a stage switch (the only plug of its kind on theground), so that it is impossible to complete the circuit until thecharger has left the gallery. That portion of the first division of thegallery which is not embedded in concrete, has a 3-in. Covering made upof blocks of magnesia, asbestos fiber, asbestos, cement, a thin layer of8-oz. Duck, and strips of water-proof roofing paper, the whole beingcovered with a thick coat of graphite paint. The object of this coveringis to assist in maintaining a constant temperature. 

 [Illustration: PLATE VII. 

 Fig. 1. --Bichel Pressure Gauges. 

 Fig. 2. --Rate of Detonation Recorder. ]

The entire gallery rests on a concrete foundation 10 ft. Wide, which hasa maximum height of 4½ ft. And a minimum height of 2 ft. 

The concrete head in which the cannon is placed completely closes thatend of the gallery. A narrow drain extends under the entire length ofthe gallery, and a tapped hole at the bottom of each section provides anefficient means of drainage. 

 [Illustration: Fig. 2. 

 {cannon as described in text} ]

The buildings near the gallery are protected by two barricades near theopen end, each 10 ft. High and 30 ft. Long. A back-stop, consisting of aswinging steel plate, 6 ft. High and 9 ft. Long, 50 ft. From the end ofthe gallery, prevents any of the stemming from doing damage. 

Tests are witnessed from an observation room, a protected position about60 ft. From the gallery. The walls of the room are 18 in. Thick, and theline of vision passes through a ½-in. Plate glass, 6 in. Wide and 37 ft. Long, and is further confined by two external guards, each 37 ft. Longand 3 ft. Wide. 

In this gallery a series of experiments has been undertaken to determinethe amount of moisture necessary with different coal dusts, in order toreduce the likelihood of a coal-dust explosion from a blown-out shot ofone of the dangerous types of explosives. 

Coal dust taken from the roads of one of the coal mines in the Pittsburgdistrict required at least 12% of water to prevent an ignition. It hasalso been proven that the finer the dust the more water is required, andwhen it was 100-mesh fine, 30% of water was required to prevent itsignition by the flame of a blown-out shot in direct contact. The methodsnow used in sprinkling have been proven entirely insufficient forthoroughly moistening the dust, and hence are unreliable in preventing ageneral dust explosion. 

At this station successful experiments have been carried out by usinghumidifiers to moisten the atmosphere after the temperature of the airoutside the gallery has been raised to mine temperature and drawnthrough the humidifiers. It has been found that if a relative humidityof 90%, at a temperature of 60° Fahr. , is maintained for 48 hours, simulating summer conditions in a mine, the absorption of moisture bythe dust and the blanketing effect of the humid air prevent the generalignition of the dust. 

These humidity tests have been run in Gas and Dust Gallery No. 1 withspecial equipment consisting of a Koerting exhauster having a capacityof 240, 000 cu. Ft. Per hour, which draws the air out of the gallerythrough the first doorway, or that next the concrete head in which thecannon is embedded. 

The other end of the gallery is closed by means of brattice cloth andpaper diaphragms, the entire gallery being made practically air-tight. The air enters the fifteenth doorway through a box, passing over steamradiators to increase its temperature, and then through the humidifierheads. 

EXPLOSIVES TESTING APPARATUS. 

There is no exposed woodwork in Building No. 17, which is 40 by 60 ft. , two stories high, and substantially constructed of heavy stone masonry, with a slate roof. The structure within is entirely fire-proof. Ironcolumns and girders, and wooden girders heavily encased in cement, support the floors which are either of cement slab construction or ofwooden flooring protected by expanded metal and cement mortar, bothabove and beneath. At one end, on the ground floor, is the exposing andrecording apparatus for flame tests of explosives, also pressure gauges, and a calorimeter, and, at the other end, is a gallery for testingsafety lamps. 

The larger portion of the second floor is occupied by a gas-tighttraining room for rescue work, and an audience chamber, from whichpersons interested in such work may observe the methods of procedure. Astorage room for rescue apparatus and different models of safety lampsis also on this floor. 

The disruptive force of explosives is determined in three ways, namely, by the ballistic pendulum, by the Bichel pressure gauge, and by Trauzllead blocks. 

_Ballistic Pendulum. _--The disruptive force of explosives, as tested bythe ballistic pendulum, is measured by the amount of oscillation. Thestandard unit of comparison is a charge of ½ lb. Of 40% nitro-glycerinedynamite. The apparatus consists essentially of a 12-in. Mortar (Fig. 3, Plate VI), weighing 31, 600 lb. , and suspended as a pendulum from a beamhaving knife-edges. A steel cannon is mounted on a truck set on a tracklaid in line with the direction of the swing of the mortar. At the timeof firing the cannon may be placed 1/16-in. From the muzzle of themortar. The beam, from which the mortar is suspended, rests on concretewalls, 51 by 120 in. At the base and 139 in. High. On top of each wallis a 1-in. Base-plate, 7 by 48 in. , anchored to the wall by ⅝-in. Bolts, 28 in. Long. The knife-edges rest on bearing-plates placed on thesebase-plates. The bearing-plates are provided with small grooves for thepurpose of keeping the knife-edges in oil and protected from theweather. The knife-edges are each 6 in. Long, 2-11/16 in. Deep frompoint to back, 2 in. Wide at the back, and taper 50° with thehorizontal, starting on a line 1½ in. From the back. The point isrounded to conform to a radius of ¼ in. The back of each is 2 in. Longerthan the edge, making a total length of 10 in. , and is 1 in. Deep and 12in. Wide. This shoulder gives bolting surface to the beam from which themortar is hung. The beam is of solid steel, has a 4 by 8-in. Section, and is 87 in. Long. Heavy steel castings are bolted to it to take thethreads of the machine-steel rods which form the saddles on which themortar is suspended. The radius of the swing, measured from the point ofthe knife-edges to the center of the trunnions, is 89¾ in. 

The cannon consists of two parts, a jacket and a liner. The jacket is 36in. Long, has an external diameter of 24 in. , and internal diameters of9½ and 7½ in. It is made of the best cast steel or of forged steel. 

The liner is 36½ in. Long, with a 1-in. Shoulder, 7¾ in. From the back, changing the diameter from 9½ to 7½ in. The bore is smooth, being 2¼ in. In diameter and 21½ in. Long. The cannon rests on a 4-wheel truck, towhich it is well braced by straps and rods. A track of 30-in. Gaugeextends about 9 ft. From the muzzle of the mortar to the bumper for thecannon. 

The shot is fired by an electric firing battery, from the first floor ofBuilding No. 17, about 10 yd. Away. To insure the safety of the operatorand the charger, the man who loads the cannon carries a safety plugwithout which the charge cannot be exploded. The wires for connecting tothe fuse after charging are placed conveniently, and the safety plug isthen inserted in a box at the end of the west wall. The completion ofthe firing battery by the switch at the firing place is indicated by theflashing of a red light, after which all that is necessary to set offthe charge is to press a button on the battery. An automatic recordingdevice at the back of the mortar records the length of swing which, by avernier, may be read to 1/200 in. 

_Bichel Pressure Gauges. _--Pressure gauges are constructed for thepurpose of determining the unit disruptive force of explosivesdetonating at different rates of velocity, by measuring pressuresdeveloped in an enclosed space from which the generated gases cannotescape. The apparatus consists of a stout steel cylinder, which may bemade absolutely air-tight; an air-pump and proper connections forexhausting the air in the cylinder to a pressure equivalent to 10 mm. Ofmercury; an insulated plug for providing the means of igniting thecharge; a valve by which the gaseous products of combustion may beremoved for subsequent analysis; and an indicator drum (Fig. 1, PlateVII) with proper connections for driving it at a determinable speed. 

This apparatus is in the southeast corner of Building No. 17. Thecylinder is 31½ in. Long, 19¾ in. In diameter, and is anchored toa solid concrete footing at a convenient height for handling. Theexplosion chamber is 19 in. Long and 7⅞in. In diameter, with a capacityof exactly 15 liters. The cover of the cylinder is a heavy piece ofsteel held in place by stout screw-bolts and a heavy steel clamp. 

The charge is placed on a small wire tripod, and connections are madewith a fuse to an electric firing battery for igniting the charges. Thecover is drawn tight, with the twelve heavy bolts against lead washers. The air in the cylinder is exhausted to 10 mm. , mercury column, in orderto approach more closely the conditions of a stemmed charge exploding ina bore-hole inaccessible to air; the indicator drum is placed inposition and set in motion; and, finally, the shot is fired. The recordshown on the indicator card is a rapidly ascending curve for quickexplosives and a shallower, slowly rising curve for explosives of slowdetonation. When the gases cool, the curve merges into a straight line, which indicates the pressures of the cooled gases on the sides of thechamber. 

 [Illustration: PLATE VIII. 

 Fig. 1. --Explosives Calorimeter. 

 Fig. 2. --Building No. 17, and Flame-Test Apparatus. 

 Fig. 3. --Small Lead Block Test. ]

Since the ratio of the volume of the cylinder to the volume of thecharge may be computed, the pressure of the confined charge may also befound, and this pressure often exceeds 100, 000 lb. Per sq. In. Thecooling effect of the inner surface on the gaseous products ofcombustion, a vital point in computations of the disruptive force ofexplosives by this method, is determined by comparing the pressuresobtained in the original cylinder with those in a second cylinder oflarger capacity, into which has been inserted one or more steelcylinders to increase the superficial area while keeping the volumeequal to that of the first cylinders. By comparing results, a curve maybe plotted, which will determine the actual pressures developed, withthe surface-cooling effect eliminated. 

_Trauzl Lead Blocks. _--The lead-block test is the method adopted by theFifth International Congress of Applied Chemistry as the standard formeasuring the disruptive force of explosives. The unit by this test isdefined to be the force required to enlarge the bore-hole in the blockto an amount equivalent to that produced by 10 grammes of standard 40%nitro-glycerine dynamite stemmed with 50 grammes of dry sand understandard conditions as produced with the tamping device. The results ofthis test, when compared with those of the Bichel gauge, indicate that, for explosives of high detonation, the lead block is quite accurate, butfor slow explosives, such as gunpowder, the expansion of the gases isnot fast enough to make comparative results of value. The reason forthis is that the gases escape through the bore of the block rather thantake effect in expanding the bore-hole. 

The lead blocks are cylindrical, 200 mm. In diameter, and 200 mm. High. Each has a central cavity, 25 mm. In diameter and 125 mm. Deep (Fig. 1, Plate IX), in which the charge is placed. The blocks are made ofdesilverized lead of the best quality, and, as nearly as possible, underidentical conditions. The charge is placed in the cavity and preparedfor detonation with an electrical exploder and stemming. After theexplosion the bore-hole is pear-shaped, the size of the cavitydepending, not only on the disruptive power of the explosive, but alsoon its rate of detonation, as already indicated. The size of thebore-hole is measured by filling the cavity with water from a burette. The difference in the capacity of the cavity before and after detonationindicates the enlarging power of the explosive. 

_Calorimeter. _--The explosion calorimeter is designed to measure theamount of heat given off by the detonation of explosive charges of 100grammes. The apparatus consists of the calorimeter bomb (Fig. 1, PlateVIII), the inner receiver or immersion vessel, a wooden tub, aregistering thermometer, and a rocking frame. This piece of apparatusstands on the east side of Building No. 17. 

The bottle-shaped bomb is made of ½-in. Wrought steel, and has acapacity of 30 liters. On opposite sides near the top are boredapertures, one for the exhaust valve for obtaining a partial vacuum(about 20 mm. , mercury column) after the bomb has been charged, theother for inserting the plug through which passes the fuse wire forigniting the charge. The bomb is closed with a cap, by which the chambermay be made absolutely air-tight. It is 30 in. High with the cap on, weighs 158 lb. , and is handled to and from the immersion vessel by asmall crane. 

The inner receiver is made of 1/16-in. Sheet copper, 30⅞ in. Deep, andwith an inner diameter of 17⅞ in. It is nickel-plated, and strengthenedon the outside with bands of copper wire, and its capacity is about 70liters. The outer tub is made of 1-in. Lumber strengthened with fourbrass hoops on the outside. It is 33 in. Deep, and its inner diameteris 21 in. 

The stirring device, operated vertically by an electric motor, consistsof a small wooden beam connected to a system of three rings having ahorizontal bearing surface. When the apparatus is put together, theinner receiver rests on a small standard on top of the base of the outertank, and the rings of the stirring device are run between the bomb andthe inner receiver. The bomb itself rests on a small standard placed onthe bottom of the inner receiver. The apparatus is provided with asnugly fitting board cover. The bomb is charged from the top, theexplosive being suspended in its center. The air is exhausted to thedesired degree of rarification. The caps are then screwed on, and theapparatus is set together as described. 

 [Illustration: PLATE IX. 

 Fig. 1. --Trauzl Lead Blocks. 

 Fig. 2. --Powder Flames. ]

The apparatus is assembled on scales and weighed before the water ispoured in and after the receiver is filled. From the weight of the waterthus obtained and the rise of temperature, the calorific value may becomputed. The charge is exploded by electricity, while the water isbeing stirred. The rise in the temperature of the water is read by amagnifying glass, from a thermometer which measures temperaturedifferences of 0. 01 degree. From the readings obtained, the maximumtemperature of explosion may be determined, according to certainformulas for calorimetric experiments. Proper corrections are made forthe effects, on the temperature readings, of the formation of theproducts of combustion, and for the heat-absorbing power of theapparatus. 

_Impact Machine. _--In Building No. 17, at the south side, is an impactmachine designed to gauge the sensitiveness of explosives to shock. Forthis purpose, a drop-hammer, constructed to meet the followingrequirements, is used: A substantial, unyielding foundation; minimumfriction in the guide-grooves; and no escape or scattering of theexplosive when struck by the falling weight. This machine is modeledafter one used in Germany, but is much improved in details ofconstruction. 

The apparatus, Fig. 1, Plate XI, consists essentially of the followingparts: An endless chain working in a vertical path and provided withlugs; a steel anvil on which the charge of explosive is held by a steelstamp; a demagnetizing collar moving freely in vertical guides andprovided with jaws placed so that the lugs of the chain may engage them;a steel weight sliding loosely in vertical guides and drawn by thedemagnetizing collar to determinable heights when the machine is inoperation; a second demagnetizing collar, which may be set at knownheights, and provided with a release for the jaws of the first collar;and a recording device geared to a vertically-driven threaded rod whichraises or lowers, sets the second demagnetizing collar, and thusdetermines the height of fall of the weight. By this apparatus theweight may be lifted to different known heights, and dropped on thesteel stamp which transmits the shock to the explosive. The fallnecessary to explode the sample is thus determined. 

The hammers are of varying weight, the one generally used weighing2, 000 grammes. As the sensitiveness of an explosive is influenced bytemperature changes, water at 25° cent. Is allowed to flow through theanvil in order to keep its temperature uniform. 

_Flame Test. _--An apparatus, Fig. 2, Plate VIII, designed to measurethe length and duration of flames given off by explosives, is placed atthe northeast corner of Building No. 17. It consists essentially of acannon, a photographing device, and a drum geared for high speed, towhich a sensitized film may be attached. 

About 13 ft. Outside the wall of Building No. 17, set in a concretefooting, is a cannon pointing vertically into an encasing cylinder orstack, 20 ft. High and 43 in. In diameter. This cannon is a duplicate ofthe one used for the ballistic pendulum, details of which have alreadybeen given. The stack or cylinder is of ¼-in. Boiler plate, intwenty-four sections, and is absolutely tight against light at the baseand on the sides. It is connected with a dark room in Building No. 17 bya light-tight conduit of rectangular section, 12 in. Wide, horizontal onthe bottom, and sloping on the top from a height of 8¼ ft. At the stackto 21 in. At the inside of the wall of the building. 

The conduit is carefully insulated from the light at all joints, and isriveted to the stack. A vertical slit, 2 in. Wide and 8 ft. Long, coincident with the center line of the conduit, is cut in the stack. Avertical plane drawn through the center line of the bore-hole of thecannon and that of the slit, if produced, intersects the center line ofa quartz lens, and coincides with the center of a stenopaic slit and theaxis of the revolving drum carrying the film. The photographingapparatus consists of a shutter, a quartz lens, and a stenopaic slit, 76by 1. 7 mm. , between the lens and the sensitized film on the rotary drum. The quartz lens is used because it will focus the ultra-violet rays, which are those attending extreme heat. 

The drum is 50 cm. In circumference and 10 cm. Deep. It is driven by a220-volt motor connected to a tachometer which reads both meters persecond and revolutions per minute. A maximum peripheral speed of 20 m. Per sec. May be obtained. 

When the cannon is charged, the operator retires to the dark room inwhich the recording apparatus is located, starts the drum, obtains thedesired speed, and fires the shot by means of a battery. When developed, the film shows a blur of certain dimensions, produced by the flame fromthe charge. From the two dimensions--height and lateraldisplacement--the length and duration of the flame of the explosive aredetermined. 

The results of flame tests of a permissible explosive and a test ofblack blasting powder, all shot without stemming, are shown on Fig. 2, Plate IX. In this test, the speed of the drum carrying the black powdernegative was reduced to one sixty-fourth of that for the permissibleexplosives, in order that the photograph might come within the limits ofthe negative. In other words, the duration of the black powder flame, asshown, should be multiplied by 64 for comparison with that of thepermissible explosive, which is from 3, 500 to 4, 000 times quicker. 

_Apparatus for Measuring Rate of Detonation. _--The rate at whichdetonation travels through a given length of an explosive can bemeasured by an apparatus installed in and near Building No. 17. Its mostessential feature is a recording device, with an electrical connection, by which very small time intervals can be measured with great exactness. 

The explosive is placed in a sheet-iron tube about 1½ in. In diameterand 4 ft. Long, and suspended by cords in a pit, 11 ft. Deep and 16 ft. In diameter. This pit was once used as the well of a gas tank, Fig. 2, Plate VIII. In adapting the pit to its new use, the tank was cut in two;the top half, inverted, was placed in the pit on a bed of saw-dust, andthe space between the tank and the masonry walls of the pit was filledwith saw-dust. The cover of the pit consists of heavy timbers framedtogether and overlaid by a 12-in. Layer of concrete reinforced by sixI-beams. Four straps extend over the top and down to eight “deadmen”planted about 8 ft. Below the surface of the ground. 

The recording device, known as the Mettegang recorder, Fig. 2, PlateVII, comprises two sparking induction coils and a rapidly revolvingmetallic drum driven by a small motor, the periphery of the drum havinga thin coating of lampblack. A vibration tachometer which will indicateany speed between 50 and 150 rev. Per sec. , is directly connected to thedrum, so that any chance of error by slipping is eliminated. The wiresleading to the primary coils of the sparking coils pass through theexplosive a meter or more apart. Wires lead from the secondary coils totwo platinum points placed a fraction of a millimeter from the peripheryof the drum. A separate circuit is provided for the firing lines. 

In making a test, the separate cartridges, with the paper trimmed fromthe ends, are placed, end to end, in the sheet-iron tube; the drum isgiven the desired peripheral speed, and the charge is exploded. Theusual length between the points in the tube is 1 m. , and the timerequired for the detonation of a charge of that length is shown by thedistance between the beginning of two rows of dots on the drum made bythe sparks from the secondary coil circuits, the dots starting theinstant the primary circuits are broken by the detonation. At one end ofthe drum are gear teeth, 1 mm. Apart on centers, which can be made toengage a worm revolving a pointer in front of a dial graduated tohundredths; by means of this and a filar eyepiece, the distance betweenthe start of the two rows of spark dots on the drum can be measuredaccurately to 0. 01 mm. As the drum is 500 mm. In circumference, and itsnormal speed is 86 rev. Per sec. , it is theoretically possible tomeasure time to one four-millionth of a second, though with a cartridge1 m. Long, such refinement has not been found necessary. 

The use of small lead blocks affords another means of determining therate of detonation or quickness of an explosive. Each block (a cylinder, 2½ in. Long and 1½ in. In diameter) is enclosed in a piece of paper sothat a shell is formed above the block, in which to place the charge. Asmall steel disk of the same diameter as the block is first placed inthe shell on top of the block, then the charge with a detonator isinserted. The charge is customarily 100 grammes. On detonation of thecharge, a deformation of the lead takes place, the amount of which isdue to the quickness of the explosive used (Fig. 3, Plate VIII). 

Sample Record of Tests. 

The procedure followed in the examination of an explosive is shown bythe following outline:

1. --_Physical Examination. _

 (_a_). --Record of appearance and marks on original package. 

 (_b_). --Dimensions of cartridge. 

 (_c_). --Weight of cartridge, color and specific gravity of powder. 

2. --_Chemical Analysis. _

 (_a_). --Record of moisture, nitro-glycerine, sodium or potassium nitrate, and other chemical constituents, as set forth by the analysis; percentage of ash, hygroscopic coefficient--the amount of water taken up in 24 hours in a saturated atmosphere, at 15° cent. , by 5 grammes, as compared with the weight of the explosive. 

 (_b_). --Analysis of products of combustion from 100 grammes, including gaseous products, solids, and water. 

 (_c_). --Composition of gaseous products of combustion, including carbon monoxide and carbon dioxide, hydrogen, nitrogen, etc. 

 (_d_). --Composition of solid products of combustion, subdivided into soluble and insoluble. 

_3. --A Typical Analysis of Natural Gas. _

Used in tests, as follows:

 Carbon dioxide 0. 0 per cent. Heavy hydrocarbons 0. 2 ” ” Oxygen 0. 1 ” ” Carbon monoxide 0. 0 ” ” Methane 82. 4 ” ” Ethane 15. 3 ” ” Nitrogen 2. 0 ” ” ----- 100. 00 per cent. 

_4. --Typical Analysis of Bituminous Coal Dust, 100-Mesh Fine, Used inTests. _

 Moisture 1. 90 Volatile matter 35. 05 Fixed carbon 58. 92 Ash 4. 13 ------ 100. 00 Sulphur 1. 04

_5. --An Average Analysis of Detonators. _

Used on Trauzl lead blocks, pressure gauge, calorimeter, and small leadblocks:

 M - l(l/m). Triple-strength exploder. 

 Charge 1. 5729 grammes. 

 Mercury Chlorate fulminate. Of potash. Specification 89. 73 10. 27

Used on all other tests:

 M - 260(l/m). Double-strength exploder. 

 Charge 0. 9805 grammes. 

 Mercury Chlorate fulminate. Of potash. Specification 91. 31 8. 69

_6. --Ballistic-Pendulum Tests. _

This record includes powder used, weight of charge, swing of mortar, andunit disruptive charge, the latter being the charge required to producea swing of the mortar equal to that produced by ½ lb. (227 grammes) of40% dynamite, or 3. 01 in. 

_7. --Record of Tests. _

Tests Nos. 1 to 5 in Gallery No. 1, as set forth in preceding circular. 

_8. --Trauzl Lead-Block Test. _

Powder and test numbers, expansion of bore-hole in cubic centimeters, and average expansion compared with that produced by a like quantity (10grammes) of 40% dynamite, the latter giving an average expansion of 294cu. Cm. 

_9. --Pressure Gauge. _

Powder and test number, weight of charge, charging density, height ofcurve, pressure developed, and pressure developed after cooling, compared with pressure developed after elimination of surface influencesby a like quantity (100 grammes) of 40% dynamite, the average being8, 439 kg. Per sq. Cm. 

_10. --Rate of Detonation. _

Powder and test number, size of cartridge, and rate of detonation inmeters per second, for comparison with rate of detonation of 40%dynamite, which, under the same conditions, averages 4, 690 m. Per sec. 

_11. --Impact Machine. _

Explosive and test numbers, distance of fall (2, 000-gramme weight)necessary to cause explosion, for comparison with length of fall, 11cm. , necessary to cause explosion of 40% dynamite. 

_12. --Distance of Explosive Wave Transmitted by 1. 25 by 8-in. Cartridge. _

Explosive and test numbers, weight of cartridge, distance separatingcartridges in tests, resulting explosion or non-explosion, forcomparison with two cartridges of 40% dynamite, hung, under identicalconditions, 13 in. Apart, end to end, in which case detonation of thefirst cartridge will explode the second. 

_13. --Flame Test. _

Explosive and test numbers, charge 100 grammes with 1 lb. Of claystemming, average length of flame and average duration of flame, forcomparison with photographs produced by 40% dynamite under likeconditions. 

 [Illustration: PLATE X. 

 Fig. 1. --Separator for Grading Black Powder. 

 Fig. 2. --Safety Lamp Testing Gallery. 

 Fig. 3. --Mine Gallery No. 2. ]

_14. --Small Lead Blocks. _

Powder and test numbers, weight of charge, and compression produced inblocks. 

_15. --Calories Developed. _

Number of large calories developed per kilogramme of explosive, forcomparison with 1, 000 grammes of 40% dynamite, which develop, on anaverage, 1, 229 large calories. 

Blasting Powder Separator. 

The grains of black blasting powder are graded by a separator, similarto those used in powder mills, but of reduced size. It consists of aninclined wooden box, with slots on the sides to carry a series ofscreens, and a vertical conduit at the end for carrying off the grainsas they are screened into separate small bins (Fig. 1, Plate X). At theupper end of the screens is a small 12 by 16-in. Hopper, with a slidingbrass apron to regulate the feed. The screens are shaken laterally by aneccentric rod operated by hand. The top of the hopper is about 6½ ft. Above the floor. The box is 6 ft. 10 in. Long, from tip to tip, andinclines at an angle of 9 degrees. 

After separation the grains fall through a vertical conduit, and thenceto the bins through zinc chutes, 1 by 2 in. In section. Care is taken tohave no steel or iron exposed to the powder. 

The screens are held by light wooden frames which slip into the inclinedbox from the upper end. In this way, any or all of the screens may beused at once, thus separating all grades, or making only suchseparations as are desired. The screens with the largest meshes arediagonally-perforated zinc plates. Table 2 gives the number of holes persquare foot in zinc plates perforated with circular holes of thediameters stated. 

 TABLE 2. --Number of Holes per Square Foot in Zinc Plates with Circular Perforations. 

 -------------+------------ Diameter, | Number in inches | of holes. -------------+------------ 1/2 | 353 4/10 | 518 1/3 | 782 1/4 | 1, 392 1/6 | 1, 680 1/8 | 3, 456 1/10 | 6, 636 1/16 | 12, 800 -------------+------------

The finer meshes are obtained by using linen screens with holes of twosizes, namely, 1/20 in. Square and 1/28 in. Square. 

Until a few years ago, black blasting powder was manufactured in thesizes given in Table 3. 

 TABLE 3. --Gradation of Black Blasting Powder. 

 ---------+----------- Grade. | Mesh. ---------+----------- CC | 2 - 2½ C | 2½ - 3 F | 3 - 5 FF | 5 - 8 FFF | 8 - 16 FFFF | 16 - 28 ---------+-----------

In late years there has been considerable demand for special sizes andmixed grains for individual mines, especially in Illinois. As nomaterial change has been made in the brands, the letters now used arenot indicative of the size of the grains, which they are supposed torepresent. Of 29 samples of black blasting powder recently received fromthe Illinois Powder Commission, only 10 were found to contain 95% of thesize of grains they were supposed to represent; 4 contained 90%; 7varied from 80 to 90%; several others were mixtures of small and largegrains, and were branded FF black blasting powder; and one samplecontained only 8. 5% of the size of grains it was supposed to represent. The remaining samples showed many variations, even when sold under thesame name. The practice of thus mixing grades is exceedingly dangerous, because a miner, after becoming accustomed to one brand of FF powder ofuniform separation, may receive another make of similar brand but ofmixed grains, and, consequently, he cannot gauge the quantity of powderto be used. The result is often an over-load or a blown-out shot. Thesmaller grains will burn first, and the larger ones may be thrown outbefore combustion is complete, and thus ignite any fire-damp present. 

Lamp Testing Gallery. 

At the Pittsburg testing station, there is a gallery for testing safetylamps in the presence of various percentages of inflammable gas. In thisgallery the safety of the lamps in these gaseous mixtures may be tested, and it is also possible for mine inspectors and fire bosses to bringtheir safety lamps to this station, and test their measurements ofpercentage of gas, by noting the length and the appearance of the flamein the presence of mixtures containing known percentages of methane andair. 

 [Illustration: PLATE XI. 

 Fig. 1. --Impact Machine. 

 Fig. 2. --Lamp Testing Box. ]

The gas-tight gallery used for testing the lamps, consists of arectangular conduit (Fig. 2, Plate X), having sheet-steel sides, 6 mm. Thick and 433 mm. Wide, the top and bottom being of channel iron. Thegallery rests on two steel trestles, and to one end is attached a No. 5Koerting exhauster, capable of aspirating 50 cu. M. Per min. , under apressure of 500 mm. Of water, with the necessary valve, steam separator, etc. The mouth of the exhauster passes through the wall of the buildingand discharges into the open air. 

Besides the main horizontal conduit, there are two secondary conduitsconnected by a short horizontal length, and the whole is put together sothat the safety lamp under test may be placed in a current of air, or ofair and gas, which strikes it horizontally, vertically upward ordownward, or at an angle of 45° (Fig. 3). The path of the current isdetermined by detachable sheet-steel doors. 

 [Illustration: Fig. 3. 

 SAFETY LAMP TESTING GALLERY]

There are five double observing windows of plate glass, which open onhinges. The size of each window is 7½ by 3 in. ; the inner glass is ¼ in. Thick and the outer one, ½ in. Thick. These glasses are separated by aspace of ¼ in. The upper conduit has four safety doors along the top, each of the inclined conduits has one safety door, and the walls andwindows are provided with rubber gaskets or asbestos packing, to makethem gas-tight. The cross-sectional area of the conduit is 434 sq. Cm. 

The air inlet consists of 36 perforations, 22 mm. In diameter, in abronze plate or diaphragm. The object of this diaphragm is to producepressure in the conduit before the mixing boxes, and permit themeasuring of the velocity of the current. The air-current, after passingthrough the holes, enters the mixer, a cast-steel box traversed by 36copper tubes, each perforated by 12 openings, 3 mm. In diameter, arranged in a spiral along its length and equally spaced. The totalcross-sectional area of the tubes is 137 sq. Cm. 

The explosive gas enters the interior of the box around the tubesthrough large pipes, each 90 mm. In diameter, passes thence through the432 openings in the copper tubes, and mixes thoroughly with the airflowing through these tubes. The current through the apparatus isinduced by the exhauster, and its course is determined by the positionof the doors. 

The gallery can be controlled so as to provide rapidly and easily acurrent of known velocity and known percentage of methane. In theexplosive current of gas and air, safety lamps of any size or design canbe tested under conditions simulating those found occasionally in mines, air-currents containing methane in dangerous proportions striking thelamps at different angles, and the relative safety of the various typesof lamps under such conditions can be determined. In this gallery it isalso possible to test lighting devices either in a quiet atmosphere orin a moving current, and, by subjecting the lamps to air containingknown percentages of methane, it is possible to acquaint the user withthe appearance of the flame caps. 

Breathing Apparatus. 

With this apparatus, the wearer may explore a gaseous mine, approachfires for the purpose of fighting them, or make investigations after anexplosion. Its object is to provide air or oxygen to be breathed by thewearer in coal mines, when the mine air is so full of poisonous gases asto render life in its presence impossible. 

A variety of forms of rescue helmets and apparatus are on the market, almost all of European manufacture, which are being subjected tocomparative trials as to their durability and safety, the ease orinconvenience involved in their use, etc. All consist essentially ofhelmets which fit air-tight about the head, or of air-tight nose clampsand mouthpieces (Fig. 1, Plate XII). 

These several forms of breathing apparatus are of three types:

1. --The liquid-air type, in which air, in a liquid state, evaporates andprovides a constant supply of fresh air. 

2. --The chemical oxygen-producing type, which artificially makes orsupplies oxygen for breathing at about the rate required; and, 3. --The compressed-oxygen type. 

 [Illustration: PLATE XII. 

 Fig. 1. --Breathing and Rescue Apparatus. 

 Fig. 2. --Rescue Training Room. ]

Apparatus of the first type, weighing 20 lb. , supplies enough air tolast about 3 hours, and the products of breathing pass through acheck-valve directly into space. Apparatus of the second type suppliesoxygen obtained from oxygen-producing chemicals, and also provides meansof absorbing the carbonic acid gas produced in respiration. They containalso the requisite tubes, valves, connections, etc. , for thetransmission of the fresh air and the respired air so as to producesufficient oxygen while in use; to absorb and purify the products ofexpiration; and to convey the fresh air to the mouth withoutcontamination by the atmosphere in which the apparatus is used. Threeoxygen-generating cartridges are provided, each supplying oxygen enoughfor 1 hour, making the total capacity 3 hours. Changes of cylinders canbe made in a few seconds while breathing is suspended. This apparatusweighs from 20 to 25 lb. , according to the number of oxygen generatorscarried. The cartridges for generating oxygen, provided with thisapparatus, are of no value after having been used for about an hour. 

The third type of apparatus is equipped with strong cylinders chargedwith oxygen under high pressure; two potash regenerative cans forabsorbing the carbon dioxide gas exhaled; a facial helmet; the necessaryvalves, tubes, etc. , for the control of the oxygen; and a finimeterwhich registers the contents of the cylinders in atmospheres and minutesof duration. The two cartridges used for absorbing the carbonic acid gasare of no value after having been in use for two hours. 

If inhalation is through the mouth alone, a mouthpiece is attached tothe end of the breathing tube by which the air or oxygen is supplied, the nose is closed by a clip, and the eyes are protected by goggles. Toinhale through both nose and mouth, the miner wears a helmet or headgearwhich can be made to fit tightly around the face. The helmet has twotubes attached, one for inspiration and the other for expiration. In theoxygen-cylinder apparatus these tubes lead to and from rubber sacks usedfor pure-air and bad-air reserves. 

Mine-Rescue Training. 

It has been found in actual service that when a miner, equipped withbreathing apparatus for the first time, enters a mine in which anexplosion has occurred, he is soon overcome by excitement or nervousnessinduced by the artificial conditions of breathing imposed by theapparatus, the darkness and heat, and the consciousness that he issurrounded with poisonous gases. It has also been found that a briefperiod of training in the use of such apparatus, under conditionssimulating those encountered in a mine after a disaster, gives the minerconfidence and enables him to use the apparatus successfully under thestrain of the vigorous exertion incident to rescue work. 

The rescue corps consists of five or six miners under the direction ofa mining engineer who is experienced in rescue operations and familiarwith the conditions existing after mine disasters. The miners work inpairs, so that one may assist the other in case of accident, or ofinjury to the breathing apparatus, and so that each may watch thecondition of the oxygen supply, as shown by the gauges in the other’soutfit. 

The training is given in the gas-tight room of Building No. 17, or insimilar rooms at sub-stations (Fig. 2, Plate XII). This room is madeabsolutely dark, and is filled with formaldehyde gas, SO_{2}, CO_{2}, orCO, produced by burning sulphur or charcoal on braziers. At each periodof training, the miners enter and walk a distance of about 1 mile, theaverage distance usually traveled from the mine mouth to the workingface or point of explosion. They then remove a number of timbers; lift aquantity of brick or hard lump-coal into wheel-barrows; climb throughartificial tunnels, up and down inclines, and over surfaces strewn withcoal or stone; operate a machine with a device attached to it, whichautomatically records the foot-pounds of work done; and perform othervigorous exercise, during a period of 2 hours. This routine is repeateddaily during 1 week, after which the rescue corps is consideredsufficiently trained for active service. 

The apparatus used for recording the foot-pounds of work done by theperson operating the work machine within the gas-tight rescue room, comprises a small dial with electrical connections, which records thenumber of strokes made by the machine, and a pencil point which rests ona paper diaphragm, fastened to a horizontal brass disk. This disk isdriven by clockwork, and makes one complete revolution per hour. Whenthe machine is in operation, the pencil point works back and forth, making a broad line on the paper; when the operator of the machinerests, the pencil point traces a single line. The apparatus thus recordsthe number of strokes given by the operator during a given time. Fromthe weight lifted, the height of lift, and the number of strokes in thegiven time, the foot-pounds of work are readily calculated. 

Electric Testing Apparatus. 

On the ground floor of Building No. 10, two rooms are occupied aslaboratories for investigating the electrical equipment used in miningoperations. The purpose of these investigations is to ascertain theconditions under which electricity of various voltages may be used withsafety--in mine haulage, hoisting, pumping, or lighting--in the presenceof dangerous mixtures of explosive gases or of dust. It is also proposedto test various kinds of insulation and insulators in this laboratory, and to determine the durability of such insulation in the presence ofsuch corrosive gases and water as are found in mines. 

A water-proof wooden tank, measuring 15 by 5 by 5 ft. , is installed, inwhich insulation and insulating materials are tested under either pureor polluted water. Various electric lighting devices and equipment canbe connected from a switch-board in Building No. 17 with Gas-and-DustGallery No. 2, for testing the effect of such lighting apparatus in thepresence of explosive mixtures of gas and dust, as set forth on page220. 

In the electrical laboratory, Building No. 10, is a booster setdeveloping 60 kw. , and an appropriate switch-board for taking directcurrent at 220 volts from the turbo-generator and converting it intocurrent varying from 0 to 750 volts. There are also transformers fordeveloping 60-cycle, alternating current at voltages of from 110 to2, 200. The switch-board is designed to handle these various voltages andto communicate them to the apparatus under test in Building No. 10, Gallery No. 2, or elsewhere. 

Tests are in progress of insulating materials for use in mines, and ofelectric fuses, lights, etc. , in Gallery No. 2 (Fig. 3, Plate X), and inthe lamp-testing box (Fig. 2, Plate XI). It is proposed, at the earliestpossible date, to make comparative tests of the safety of various minelocomotives and mine-hoisting equipment through the medium of thislaboratory, and it is believed that the results will furnish valuableinformation as a guide to the safety, reliability, and durability ofthese appliances when electrically operated. 

_Electric Lamp and Fuse Testing Box. _--An apparatus for testing safetylamps and electric lights and fuses, consists of ¼-in. Iron plates, bolted together with 1½ in. Angle-irons to form a box with insidedimensions of 18 by 18 by 24 in. The box is placed on a stand at such aheight that the observation windows are on a level with the observer’seye (Fig. 2, Plate XI), and it is connected, by a gas-pipe, with asupply of natural gas which can be measured by a gas-holder or meteralongside the box. 

By the use of this apparatus the effect of explosive gas on flames, ofelectric sparks on explosive mixtures of gas and air, and of breakingelectric lamps in an explosive mixture of gas and air, may be studied. The safety lamps are introduced into the box from beneath, through ahole 6 in. Square, covered with a hinged iron lid, admission to which ishad through a flexible rubber sleeve, 20 in. Long. 

The behavior of the standard safety lamp and of the safety lampsundergoing test may be compared in this box as to height of flame fordifferent percentages of methane in the air, the effect of such flamesin igniting gas, etc. 

In each end of the box is an opening 1 ft. Square, over which may beplaced a paper diaphragm held by skeleton doors, the purpose of whichis to confine the gas in such a manner that, should an explosion occur, no damage would be done. In the front of the box are two plate-glassobserving windows, 2⅝ by 5½ in. In the side of the box, between thetwo windows, is a ⅜-in. Hole, which can be closed by a tap-screw, through which samples for chemical analysis are drawn. 

The gasometer consists of two iron cans, the lower one being open atthe top and filled with water and the upper one open at the bottom andsuspended by a counterweight. The latter has attached to its uppersurface a scale which moves with it, thereby measuring the amount ofgas in the holder. A two-way cock permits the admission of gas into thegasometer and thence into the testing box. 

_Gas-and-Dust Gallery No. 2. _--This gallery is constructed of sheetsteel and is similar to Gallery No. 1, the length, however, being only30 ft. And the diameter 10 ft. It rests on a concrete foundation (Fig. 3, Plate X). Diaphragms can be placed across either extremity, or atvarious sections, to confine the mixtures of gas and air in which thetests are made. The admission of gas is controlled by pipes and valves, and the gas and air can be stirred or mixed by a fan, as described forGallery No. 1, and as shown by Fig. 1. 

Gallery No. 2 is used for investigating the effect of flames of variouslamps, of electric currents, motors, and coal-cutting machines, in thepresence of known mixtures of explosive gas and air. It is also used fortesting the length of flame of safety lamps in still air carryingvarious proportions of methane, and, for this purpose, is moreconvenient than the lamp gallery. In tests with explosive mixtures, after the device to be tested has been introduced and preparations arecompleted, operations are controlled from a safe distance by aswitch-board in a building near-by. 

Among other investigations conducted in this gallery are those of theeffect of sparks on known gas mixtures. These sparks are such as thosestruck from a pick on flint, but in this case they are produced byrubbing a rapidly revolving emery wheel against a steel file. The effectof a spark produced by a short circuit of known voltage, the flame froman arc lamp, etc. , may also be studied in this gallery. 

STRUCTURAL MATERIALS INVESTIGATIONS. 

The structural materials investigations are being conducted for thepurpose of determining the nature and extent of the materials availablefor use in the building and construction work of the Government, and howthese materials may be used most efficiently. 

These investigations include:

(1). --Inquiries into the distribution and local availability, near eachof the building centers in the United States, of such materials as areneeded by the Government. 

(2). --How these materials may be used most efficiently. 

(3). --Their fire-resisting qualities and strength at differenttemperatures. 

(4). --The best and most economic methods of protecting steel byfire-resistant covering. 

(5). --The most efficient methods of proportioning and mixing theaggregate, locally available, for different purposes. 

(6). --The character and value of protective coatings, or of variousmixes, to prevent deterioration by sea water, alkali, and otherdestructive agencies. 

(7). --The kinds and forms of reinforcement for concrete necessary tosecure the greatest strength in beams, columns, floor slabs, etc. 

(8). --Investigation of the clays and of the products of clays needed inGovernment works, as to their strength, durability, suitability asfire-resisting materials, and the methods of analyzing and testing clayproducts. 

(9). --Tests of building stones, and investigations as to theiravailability near the various building centers throughout the UnitedStates. 

The operations of the Structural Materials Division includeinvestigations into cement-making materials, constituent materials ofconcrete, building stones, clays, clay products, iron, steel, andmiscellaneous materials of construction, for the use of the Government. The organization comprises a number of sections, including those for thechemical and physical examination of Departmental purchases; fieldsampling and laboratory examination of constituent materials of concretecollected by skilled field inspectors in the neighborhood of the largercommercial and building centers; similar field sampling of buildingstones and of clays and clay products, offered for use in Governmentbuildings or engineering construction; and the forwarding of suchsamples to the testing laboratories at St. Louis or Pittsburg forinvestigation and test. The investigative tests include experimentsregarding destructive agencies, such as electrolysis, alkaline earthsand waters, salt water, fire, and weathering; also experiments withprotective and water-proofing agencies, including the various washes orpatented mixtures on the market, and the methods of washing, and mixingmortars and concrete, which are likely to result in rendering suchmaterials less pervious to water. 

Investigations are also being conducted to determine the nature andextent of materials available for use in the building-construction workof the Government, and how these materials may be used most efficientlyand safely. While the act authorizing this work does not permitinvestigations or tests for private parties, it is believed that thesetests for the Government cannot fail to be of great general value. Theaggregate expenditure by the Federal Government in building andengineering construction is about $40, 000, 000 annually. This work isbeing executed under so many different conditions, at points so widelyseparated geographically, and requires so great a variety of materials, that the problems to be solved for the Government can hardly fail tocover a large share of the needs of the Engineering Profession, Stateand municipal governments, and the general public. 

_Character of the Work. _--The tests and analyses, of the materials ofconstruction purchased by the various bureaus and departments for theuse of the Government, are to determine the character, quality, suitability, and availability of the materials submitted, and toascertain data leading to more accurate working values as a basis forbetter working specifications, so as to enable Government officials touse such materials with more economy and increased efficiency. 

Investigative tests of materials entering into Government construction, relative to the larger problems involved in the use of materialspurchased by the Government, include exhaustive study of the suitabilityfor use, in concrete construction on the Isthmian Canal, of the sand andstone, and of the cementing value of pozzuolanic material, found on theIsthmus; the strength, elasticity, and chemical properties of structuralsteel for canal lock-gates; of wire rope and cables for use in hoistingand haulage; and the most suitable sand and stone available for concreteand reinforced concrete for under-water construction, such as theretaining walls being built by the Quartermaster’s Department of theArmy, in San Francisco Harbor. 

These tests also include investigations into the disintegrating effectof alkaline soil and water on the concrete and reinforced concretestructures of the Reclamation Service, with a view to preventing suchdisintegration; investigations into the proper proportions anddimensions of concrete and reinforced concrete structural columns, beams, and piers, and of walls of brick and of building stone, and ofthe various types of metal used for reinforcement by the SupervisingArchitect in the construction of public buildings; investigations intothe sand, gravel, and broken stone available for local use in concreteconstruction, such as columns, piers, arches, floor slabs, etc. , as aguide to the more economical design of public structures, and todetermine the proper method of mixing the materials to render theconcrete most impervious to water and resistant to weather and otherdestructive agencies. 

Other lines of research may be stated briefly as follows:

The extent to which concrete made from cement and local materials can bemost safely and efficiently used for different purposes under differentconditions;

The best methods for mixing and utilizing the various constituentmaterials locally available for use in Government construction;

The materials suitable for the manufacture of cement on the publiclands, or where the Government has planned extensive building orengineering construction work, where no cement plants now exist;

The kinds and forms of reinforcement for concrete, and the best methodsof applying them in order to secure the greatest strength incompression, tension, shear, etc. , in reinforced concrete beams, columns, floor slabs, etc. ;

The influence of acids, oils, salts, and other foreign materials, long-continued strain, or electric currents, on the permanence of thesteel in reinforced concrete;

The value of protective coatings as preventives of deterioration ofstructural materials by destructive agencies; and

The establishment of working stresses for various structural materialsneeded by the Government in its buildings. 

Investigations are being made into the effects of fire and the rate ofconductivity of heat on concrete and reinforced concrete, brick, tile, building stone, etc. , as a guide to the use of the most suitablematerials for fire-proof building construction and the properdimensioning of fire-resistive coverings. 

Investigations and tests are being made, with a view to the preparationof working specifications for use in Government construction, of bricks, tile, sand-lime brick, paving brick, sewer pipe, roofing slates, flooring tiles, cable conduits, electric insulators, architectural terracotta, fire-brick, and all shapes of refractories and other clayproducts, regarding which no satisfactory data for the preparation ofspecifications of working values now exist. 

Investigations of the clay deposits throughout the United States are inprogress, to determine proper methods of converting them into buildingbrick, tile, etc. , at the most reasonable cost, and the suitability ofthe resulting material for erection in structural forms and to meetbuilding requirements. 

Investigations are being made in the field, of building stones locallyavailable, and physical and chemical tests of these building stones todetermine their bearing or crushing strength; the most suitable mortarsfor use with them; their resistance to weathering; their fire-resistiveand fire-proof qualities, etc. , regarding which practically no adequateinformation is available as a guide to Government engineering andbuilding design. 

_Results Accomplished. _--During one period of six months alone, morethan 2, 500 samples, taken from Government purchases of structuralmaterials, were examined, of which more than 300 failed to meet thespecified requirements, representing many thousands of dollars worth ofinferior material rejected, which otherwise would have been paid for bythe Government. These tests were the means of detecting the inferiorquality of large quantities of materials delivered on contracts, and themoral effect on bidders has proven as important a factor in themaintenance of a high quality of purchases, as in the saving of money. 

The examination of sands, gravels, and crushed stones, as constituentmaterials for concrete and reinforced concrete construction, hasdeveloped data showing that certain materials, locally available nearlarge building centers and previously regarded as inferior in quality, were, in fact, superior to other and more expensive materials which ithad been proposed to use. 

These investigations have represented an actual saving in the cost ofconstruction on the work of the Isthmian Canal Commission, of theSupervising Architect, and of certain States and cities which havebenefited by the information disseminated regarding these constituentmaterials. 

Investigations of clay products, only recently inaugurated, have alreadyresulted in the ascertainment of important facts relative to the colloidmatter of clay and its measurement, and the bearing thereof on theplasticity and working values of various clays. The study of thepreliminary treatment of clays difficult to handle dry, has furnisheduseful information regarding the drying of such clays, and concerningthe fire resistance of bricks made of soft, stiff, or dried clay ofvarious densities. 

The field collection and investigation of building-stone samples havedeveloped some important facts which had not been considered previously, relative to the effect of quarrying, in relation to the strike and dipof the bedding planes of building stone, and the strength and durabilityof the same material when erected in building construction. Theseinvestigations have also developed certain fundamental facts relative tothe effects of blasting (as compared with channeling or cutting) on thestrength and durability of quarried building stone. 

_Mineral Chemistry Laboratories. _--Investigations and analyses of thematerials of engineering and building construction are carried on atPittsburg in four of the larger rooms of Building No. 21. In thislaboratory, are conducted research investigations into the effect ofalkaline waters and soils on the constituent materials of concreteavailable in arid regions, as related to the life and permanency of theconcrete and reinforced concrete construction of the ReclamationService. These investigations include a study of individual salts foundin particular alkalis, and a study of the results of allowing solutionsof various alkalis to percolate through cylinders of cement mortar andconcrete. Other research analyses have to do with the investigation ofdestructive and preservative agencies for concrete, reinforced concrete, and similar materials, and with the chemistry of the effects of saltwater on concrete, etc. The routine chemical analyses of the constituentmaterials of concrete and cement-making materials, are made in thislaboratory, as are also a large number of miscellaneous chemicalanalyses and investigations of reinforcement metal, the composition ofbuilding stones, and allied work. 

A heat laboratory, in charge of Dr. J. K. Clement, occupies three roomson the ground floor of Building No. 21, and is concerned chiefly withthe measurement of temperatures in gas producers, in the furnaces ofsteam boilers, kilns, etc. The work includes determinations of thethermal conductivity of fire clays, concrete, and other buildingmaterials, and of their fire-resisting properties; measurements of thethermal expansion and specific heats of fire-bricks, porcelain, andglazes; and investigations of the effect of temperature variations onthe various chemical processes which take place in the fuel bed of thegas producer, boiler furnace, etc. 

The heat laboratory is equipped for the calibration of the thermometersand pyrometers, and electrical and other physical apparatus used by thevarious sections of the Technologic Branch. 

For convenience in analyzing materials received from the variouspurchasing officers attached to the Government bureaus, this work ishoused in a laboratory on the fourth floor of the Geological SurveyBuilding in Washington. 

Large quantities and many varieties of building materials for use inpublic buildings under contract with the Supervising Architect’s office, are submitted to the laboratory by contractors to determine whether ornot they meet the specified requirements. Further examinations are madeof samples submitted by superintendents of construction, representingmaterial actually furnished by contractors. It is frequently found thatthe sample of material submitted by the contractor is of far betterquality than that sent by the superintendent to represent deliveries. The needed constant check on deliveries is thus provided. 

In addition to this work for the office of the Supervising Architect, similar work on purchases and supplies is carried on for the IsthmianCanal Commission, the Quartermaster-General’s Department of the Army, the Life Saving Service, the Reclamation Service, and other branches ofthe Government. About 300 samples are examined each month, requiring anaverage of 12 determinations per sample, or about 3, 600 determinationsper month. 

The chemical laboratory for testing Government purchases of structuralmaterials is equipped with the necessary apparatus for making therequisite physical and chemical tests. For the physical tests of cement, there are a tensile test machine, briquette moulds, a pat tank forboiling tests to determine soundness, water tanks for the storage ofbriquettes, a moist oven, apparatus to determine specific gravity, fineness of grinding, etc. 

The chemical laboratory at Washington is equipped with the necessaryanalytical balances, steam ovens, baths, blast lamps, stills, etc. , required in the routine chemical analysis of cement, plaster, clay, bricks and terra cotta, mineral paints and pigments, roofing material, tern plate and asphaltic compounds, water-proofing materials, iron andsteel alloys, etc. 

At present, materials which require investigative tests as a basis forthe preparation of suitable specifications, tests not connected with theimmediate determination as to whether or not the purchases are inaccordance with the specifications, are referred to the chemicallaboratories attached to the Structural Materials Division, atPittsburg. 

The inspection and tests of cement purchased in large quantities, suchas the larger purchases on behalf of public-building construction underthe Supervising Architect, or the great 4, 500, 000-bbl. Contract of theIsthmian Canal Commission, are made in the cement-testing laboratory ofthe Survey, in the Lehigh Portland cement district, at Northampton, Pa. 

_Testing Machines. _--The various structural forms into which concreteand reinforced concrete may be assembled for use in public-buildingconstruction, are undergoing investigative tests as to their compressiveand tensile strength, resistance to shearing, modulus of elasticity, coefficient of expansion, fire-resistive qualities, etc. Similar testsare being conducted on building stone, clay products, and the structuralforms in which steel and iron are used for building construction. 

The compressive, tensile, and other large testing machines, for allkinds of structural materials reaching the testing stations, are underthe general supervision of Richard L. Humphrey, M. Am. Soc. C. E. Theimmediate direction of the physical tests on the larger testing machinesis in charge of Mr. H. H. Kaplan. 

Most of this testing apparatus, prior to 1909, was housed in buildingsloaned by the City of St. Louis, in Forest Park, St. Louis, Mo. , and thearrangement of these buildings, details of equipment, organization, andmethods of conducting the tests, are fully set forth in Bulletin No. 329of the U. S. Geological Survey. In brief, this equipment includedmotor-driven, universal, four-screw testing machines, as follows: One600, 000-lb. , vertical automatic, four-screw machine; one 200, 000-lb. , automatic, four-screw machine; and one 200, 000-lb. And one 100, 000-lb. Machine of the same type, but with three screws. There are a number ofsmaller machines of 50, 000, 40, 000, 10, 000, and 2, 000 lb. , respectively. 

These machines are equipped so that all are available for making tensileand compressive tests (Fig. 1, Plate XIII). The 600, 000-lb. Machine iscapable of testing columns up to 30-ft. Lengths, and of makingtransverse tests of beams up to 25-ft. Span, and tension tests forspecimens up to 24 ft. In length. The smaller machines are capable ofmaking tension and compressive tests up to 4 ft. In length andtransverse beam tests up to 12 ft. Span. In addition, there are amplesubsidiary apparatus, including concrete mixers with capacities of ½ and1 cu. Yd. , five hollow concrete block machines, automatic siftingmachines, briquette moulds, storage tanks, etc. 

At the Atlantic City sub-station, there is also a 200, 000-lb. , universal, four-screw testing machine, with miscellaneous equipment fortesting cement and moulding concrete, etc. ; and at the Northamptonsub-station, there is a complete equipment of apparatus for cementtesting, capable of handling 10, 000 bbl. Per day. 

At the Pittsburg testing station, a 10, 000, 000-lb. , vertical, compression testing machine (Plate XIV), made by Tinius Olsen andCompany, is being erected for making a complete series of comparativetests of various building stones of 2, 4, and 12-in. Cube, of stoneprisms, 12 in. Base and 24 in. High, of concrete and reinforced concretecolumns up to 65 ft. In height, and of brick piers and structural-steelcolumns up to the the limits of the capacity and height of the machine. 

 [Illustration: PLATE XIII. 

 Fig. 1. --Testing Beam in 200, 000-Lb. Machine. 

 Fig. 2. --Fire Test of Panel. ]

This machine is a large hydraulic press, with an adjustable head, and aweighing system for recording the loading developed by a triple-plungerpump. It has a maximum clearance of 65 ft. Between heads; the clearancein the machine is a trifle more than 6 ft. Between screws, and the headsare 6 ft. Square. 

The machine consists of a base containing the main cylinder, with asectional area of 2, 000 sq. In. , upon which rests the lower platform orhead, which is provided with a ball-and-socket bearing. The upper headis adjustable over four vertical screws, 13½ in. In diameter and 72 ft. 2 in. Long, by a system of gearing operating four nuts withball-bearings upon which the head rests. The shafting operating thismechanism is connected with a variable-speed motor which actuatesthe triple-plunger pump supplying the pressure to the main cylinder(Fig. 4). 

The weighing device consists of a set of standard Olsen levers forweighing one-eightieth of the total load on the main cylinder. Thisreduction is effected through the medium of a piston and a diaphragm. The main cylinder has a diameter of 50 in. , and the smaller one, adiameter of 5-9/16 in. The weighing beam is balanced by anautomatically-operated poise weight, and is provided with a device forapplying successive counterweights of 1, 000, 000 lb. Each. Each divisionon the dial is equivalent to a 100-lb. Load, and smaller subdivisionsare made possible by an additional needle-beam. 

The power is applied by a 15-h. P. , 220-volt, variable-speed motoroperating a triple-plunger pump, the gearing operating the upper headbeing driven by the same motor. The extreme length of the main screwsnecessitates splicing, which is accomplished as follows:

In the center of the screws, at the splice, is a 3-in. Threaded pin forcentering the upper and lower screws; this splice is strengthened bysleeve nuts, split to facilitate their removal whenever it is necessaryto lower the upper head; after the head has passed the splice, thesleeve nuts are replaced. 

In order to maintain a constant load, a needle-valve has been provided, which, when the pump is operated at its lowest speed, will allow asufficient quantity of oil to flow into the main cylinder to equalizewhatever leakage there may be. The main cylinder has a vertical movementof 24 in. The speed of the machine, for the purpose of adjustment, usingthe gearing attached to the upper head, is 10 in. Per min. The speed forapplying loads, controlled by the variable-speed motor driving the pump, varies from a minimum of at least 1/60 in. Per min. To a maximum of atleast ½ in. Per min. The machine has a guaranteed accuracy of at leastone-third of 1%, for any load of more than 100, 000 lb. , up to itscapacity. 

 [Illustration: Fig. 4. 

 PLAN AND ELEVATION OF 10, 000, 000-LB. VERTICAL COMPRESSION TESTING MACHINE]

The castings for the base and the top head weigh approximately 48, 000lb. Each. Each main screw weighs more than 40, 000 lb. , the lowerplatform weighing about 25, 000 lb. , and the main cylinder, 16, 000 lb. The top of the machine will be about 70 ft. Above the top of the floor, and the concrete foundation, upon which it rests, is about 8 ft. Belowthe floor line. 

 [Illustration: PLATE XIV. 

 10, 000, 000-Lb. Testing Machine. ]

_Concrete and Cement Investigations. _--The investigations relating toconcrete include the examination of the deposits of sand, gravel, stone, etc. , in the field, the collection of representative samples, and theshipment of these samples to the laboratory for analysis and test. Thesetests are conducted in connection with the investigation of cementmortars, made from a typical Portland cement prepared by thoroughlymixing a number of brands, each of which must meet the followingrequirements:

 Specific gravity, not less than 3. 10;

 Fineness, residue not to exceed 8% on No. 100, nor 25% on No. 200 sieve;

 Time of setting: Initial set, not less than 30 min. ; hard set, not less than 1 hour, nor more than 10 hours. 

 Tensile strength: Requirements applying to neat cement and to 1 part cement with 3 parts standard sand:

 -------------------------------+--------------+---------- | Neat cement. | 1:3 Mix. Time specification. | Pounds. | Pounds. -------------------------------+--------------+---------- 24 hours in moist air | 175 | ... 7 days (1 day in moist air, | 500 | 175 6 days in water) | | 28 days (1 day in moist air, | 600 | 250 27 days in water) | | -------------------------------+--------------+----------

 Constancy of volume: Pats of neat cement, 3 in. In diameter, ½ in. Thick at center, tapering to a thin edge, shall be kept in moist air for a period of 24 hours. A pat is kept in air at normal temperature and observed at intervals for at least 28 days. Another pat is kept in water maintained as near 70° Fahr. As practicable, and is observed at intervals for at least 28 days. A third pat is exposed in an atmosphere of steam above boiling water, in a loosely-closed vessel, for 5 hours. These pats must remain firm and hard and show no signs of distortion, checking, cracking, or disfiguration. 

 The cement shall not contain more than 1. 75% of anhydrous sulphuric acid, nor more than 4% of magnesium oxide. 

 A test of the neat cement must be made with each mortar series for comparison of the quality of the typical Portland cement. 

The constituent materials are subjected to the following examination anddeterminations, and, in addition, are analyzed to determine thecomposition and character of the stone, sand, etc. :

 1. --Mineralogical examination, 2. --Specific gravity, 3. --Weight, per cubic foot, 4. --Sifting (granulometric composition), 5. --Percentage of silt and character of same, 6. --Percentage of voids, 7. --Character of stone as to percentage of absorption, porosity, permeability, compressive strength, and behavior under treatment. 

Physical tests are made to determine the tensile, compressive, andtransverse strengths of the cement and mortar test pieces, with variouspreparations of cement and various percentages of material. Tests arealso made to determine porosity, permeability, volumetric changes insetting, absorption, coefficient of expansion, effect of oil, etc. 

Investigation of concretes made from mixtures of typical Portlandcement, sand, stone, and gravel, includes tests on cylinders, prisms, cubes, and other standard test pieces, with various proportions ofmaterials and at ages ranging from 30 to 360 days. Full-sized plainconcrete beams, moulded building blocks, reinforced concrete beams, columns, floor slabs, arches, etc. , are tested to determine the effect, character, and amount of reinforcement, the effect of changes in volume, size, and composition, and the effect of different methods of loadingand of supporting these pieces, etc. 

These investigations include detailed inquiry in the field and researchin the chemical and physical laboratories regarding the effects ofalkaline soils and waters on structures of concrete being built by theReclamation Service in the arid regions. It has been noted that oncertain of the Reclamation projects, notably on the Sun River Project, near Great Falls, Mont. , the Shoshone Project, near Cody, Wyo. , and theCarlsbad and Hondo Projects in the Pecos Valley, N. Mex. , structures ofconcrete, reinforced concrete, building stones, brick, and tile, showevidence of disintegration. This is attributed to the effects ofalkaline waters or soils coming into contact with the structures, or tothe constituent materials used. In co-operation with the ReclamationService, samples of the waters, soils, and constituent materials, arecollected in the field, and are subjected to careful chemicalexamination in the mineral laboratories at Pittsburg. 

 [Illustration: PLATE XV. 

 Fig. 1. --Characteristic Failures of Reinforced Concrete Beams. 

 Fig. 2. --Arrangement of Static Load Test for Reinforced Concrete Beams. ]

The cylinders used in the percolation tests are composed of typicalPortland cement mixed with sand, gravel, and broken stone of knowncomposition and behavior, and of cement mixed with sand, gravel, andbroken stone collected in the neighborhood of the Reclamation projectsunder investigation. 

 [Illustration: Fig. 5. 

 CROSS-SECTION OF APPARATUS FOR HOLDING PERMEABILITY-TEST PIECES]

It is also proposed to subject these test pieces, some made with waterof known purity, and others with alkaline water, to contact withalkaline soils near the projects, and with soil of known compositionnear the testing laboratories at Pittsburg. As these tests progress andother lines of investigation are developed, the programme will beextended, in the hope that the inquiry may develop methods of preparingand mixing concrete and reinforced concrete which can be used inalkaline soils without danger of disintegration. 

Investigations into the effect of salt water on cement mortars andconcretes, and the effect of electrolysis, are being conducted atAtlantic City, N. J. , where the test pieces may be immersed in deep seawater for longer or shorter periods of time. 

At the Pittsburg laboratory a great amount of investigative work is donefor the purpose of determining the suitability and availability ofvarious structural materials submitted for use by the Government. Whileprimarily valuable only to the Government, the results of these testsare of indirect value to all who are interested in the use of similarmaterials. Among such investigations have been those relating to thestrength, elasticity, and chemical properties of wire rope for use inthe Canal Zone; investigations of the suitability and cementing value ofconcrete, sand, stone, and pozzuolanic material found on the Isthmus;investigations as to the relative resistance to corrosion of varioustypes of wire screens for use in the Canal Zone; into the suitabilityfor use, in concrete sea-wall construction, of sand and stone from thevicinity of San Francisco; into the properties of reinforced concretefloor slabs; routine tests of reinforcing metal, and of reinforcedconcrete beams and columns, for the Supervising Architect of theTreasury Department, etc. The results have been set forth in threebulletins[9] which describe the methods of conducting these tests andalso tests on constituent materials of concrete and plain concretebeams. In addition, there are in process of publication a number ofbulletins giving the results of tests on reinforced concrete beams, columns, and floor slabs, concrete building blocks, etc. 

The Northampton laboratory was established because it is in the centerof the Lehigh cement district, and therefore available for the millsampling and testing of purchases of cement made by the Isthmian CanalCommission; it is also available for tests of cement purchased in theLehigh district by the Supervising Architect and others. It is in abuilding, the outer walls of which are of cement plaster applied overmetal lath nailed to studding. The partitions are of the sameconstruction, and the floors and roof are of concrete throughout. 

The inspection at the factories and the sampling of the cement are underthe immediate direction of the Commission; the testing is under thedirection of the U. S. Geological Survey. A large force of employees isrequired, in view of the magnitude of the work, which includes the dailytesting of consignments ranging from 5, 000 to 10, 000 bbl. , sampled inlots of 100 bbl. , which is equivalent to from 50 to 100 samples testedper day. 

The cement to be sampled is taken from the storage bins and kept underseal by the chief inspector pending the results of the test. Thequantity of cement sampled is sufficient for the tests required underthe specifications of the Isthmian Canal Commission, as well as forpreliminary tests made by the cement company, and check tests made atthe Geological Survey laboratory, at Pittsburg. 

The tests specified by the Commission include determination of specificgravity, fineness of grinding, time of setting, soundness, tensilestrength (with three parts of standard quartz sand for 7 and 28 days, respectively), and determination of sulphur anhydride (SO_{3}), andmagnesia (MgO). 

The briquette-making and testing room is fitted with a mixing table, moist closet, briquette-storage tanks, and testing machines. The mixingtable has a concrete top, in which is set plate glass, 18 in. Square and1 in. Thick. Underneath the table are shelves for moulds, glass plates, etc. 

The moist closet, 5 ft. High, 3 ft. 10 in. Wide, and 1 ft. 8 in. Deep, is divided into two compartments by a vertical partition, and eachcompartment is fitted with cleats for supporting thirteen tiers of glassplates. On each pair of cleats, in each compartment, can be placed fourglass plates, each plate containing a 4-gang mould, making storage for416 briquettes. With the exception of the doors, which are of wood linedwith copper, the closet is of 1:1 cement mortar, poured monolithic, evento the cleats for supporting the glass plates. 

The immersion tanks, of the same mortar, are in tiers of three, supported by a steel structure. They are 6¼ ft. Long, 2¼ ft. Wide, and 6in. Deep, and 2, 000 briquettes can be stored in each tank. The overflowfrom the top tank wastes into the second, which, in turn, wastes intothe third. Water is kept running constantly. 

The briquette-testing machine is a Fairbanks shot machine with acapacity of 2, 000 lb. , and is regulated to apply the load at the rate of600 lb. Per min. Twenty-four 4-gang moulds, of the type recommended bythe Special Committee on Uniform Tests of Cement, of the AmericanSociety of Civil Engineers, are used. 

The room for noting time of set and soundness is fitted with a mixingtable similar to that in the briquette-making room. The Vicat apparatusis used for determining the normal consistency, and the Gilmoreapparatus for the time of setting. While setting, the soundness pats arestored in galvanized-iron pans having about 1 in. Of water in thebottom, and covered with dampened felt or burlap. The pats rest on arack slightly above the water and well below the felt. 

For specific gravity tests, the Le Chatelier bottles are used. A pan, inwhich five bottles can be immersed at one time, is used for maintainingthe benzine at a constant temperature. The samples are weighed on a pairof Troemner’s No. 7 scales. 

The fineness room is fitted with tables, two sets of standard No. 100and No. 200 sieves, and two Troemner’s No. 7 scales similar to thoseused for the specific gravity tests. 

The storage room is fitted with shelves for the storage of samples beingheld for 28-day tests. 

The mould-cleaning room contains tables for cleaning moulds, and racksfor air pats. 

An effort is made to keep all the rooms at a temperature of 70° Fahr. , and, with this in view, a Bristol recording thermometer is placed in thebriquette-room. Two wet-and-dry bulb hygrometers are used to determinethe moisture in the air. 

Samples are taken from the conveyor which carries the cement to thestorage bins, at the approximate rate of one sample for each 100 bbl. After each 4, 000-bbl. Bin has been filled, it is sealed until all testshave been made, when, if these have been satisfactory, it is releasedfor shipment. 

The samples are taken in cans, 9 in. High and 7½ in. In diameter. Thesecans are delivered in the preparation room where the contents are mixedand passed through a No. 20 sieve. Separate samples are then weighed outfor mortar briquettes, for soundness pats, and for the specific-gravityand fineness tests. These are placed in smaller cans and a quantitysufficient for a re-test is held in the storage room awaiting theresults of all the tests. 

The sample for briquettes is mixed with three parts standard crushedquartz, and then taken to the briquette-making room, where eightbriquettes are made, four for 7-day and four for 28-day tests. These areplaced in the moist closet in damp air for 24 hours, then removed fromthe moulds, and placed in water for the remainder of the test period. Atthe proper time they are taken from the immersion tank and broken. 

From the sample for soundness, four pats are made. The time of settingis determined on one of these pats. They are placed in the panpreviously described, for 24 hours, then one is placed in running waterand one in air for 28 days. The others are treated in the boiler, one inboiling water for 3 hours and one in steam at atmospheric pressure for 5hours. 

The sample taken for specific gravity and fineness is dried in the ovenat 100° cent. In order to drive off moisture. Two samples are thencarefully weighed out, 50 grammes for fineness and 64 grammes forspecific gravity, and the determinations are made. As soon as anythingunsatisfactory develops, a re-test is made. If, however, the cementsatisfies all requirements, a report sheet containing all the data for abin, is made out, and the cement is ready for shipment. From every fifthbin, special neat and mortar briquettes are made, which are intended fortests at ages up to ten years. 

_Salt-Water Laboratory. _--The laboratory at Atlantic City, forconducting investigations into the effects of salt water on concrete andreinforced concrete, is situated so that water more than 25 ft. Deep isavailable for immersion tests of the setting and deterioration of suchmaterials. 

Through the courtesy of the municipality of Atlantic City, Young’scottage, on old Young’s Pier, has been turned over, at a nominal rental, to the Geological Survey for the conduct of these tests. The laboratorybuilding is about 700 ft. From the boardwalk, and occupies a space about100 by 45 ft. It is one story high, of frame-cottage construction, andstands on wooden piles at one side of the pier proper and about 20 ft. Above the water, which is about 19 ft. Deep at this point. Fresh runningwater, gas, electric light, and electric power are supplied to thebuilding (Fig. 6). 

In this laboratory investigations will be made of the cause of thefailure and disintegration of cement and concrete subjected to theaction of sea water. Tests are conducted so as to approach, as nearly aspossible, the actual conditions found in concrete construction along thesea coast. All sea-water tests are made in the ocean, some will probablybe paralleled by ocean-water laboratory tests and all by fresh-watercomparative tests. 

Cements, in the form of pats, briquettes, cubes, cylinders, and in aloose ground state, and also mortars and concretes in cube, cylinder, and slab form, are subjected to sea water. 

The general plan for the investigations is as follows:

1. --Determination of the failing elements and the nature of the failure;

2. --Determination of the value of the theories advanced at the presenttime; and, 3. --Determination of a method of eliminating or chemically recombiningthe injurious elements. 

Preliminary tests are in progress, including a study of the effect ofsalt water on mortars and concretes of various mixtures and ages. Theproportions of these mixtures and the methods of mixing will be variedfrom time to time, as suggested by the progress of the tests. 

_Fire-Proofing Tests. _--Tests of the fire-proofing and fire-resistiveproperties of various structural materials are carried on in thelaboratories in Building No. 10, at Pittsburg, and in co-operation withthe Board or Fire Underwriters at its Chicago laboratory (Fig. 2, PlateXIII). These tests include three essential classes of material: (_a_), clay products, protective coverings representative of numerous varietiesof brick and fire-proofing tiles, including those on the market andthose especially manufactured for these tests in the laboratory atPittsburg; (_b_), characteristic granites of New England, withsubsequent tests of the various building stones found throughout theUnited States; and (_c_), cement and concrete covering material, building blocks, and concrete reinforced by steel bars embedded atdifferent depths for the purpose of studying the effect of expansion onthe protective covering. 

In co-operation with the physical laboratory, these tests include astudy of the relative rates of conductivity of cement mortars andconcretes. By embedding thermo-couples in cylinders composed of thematerials under test, obtaining a given temperature by an electric coil, and noting the time required to raise the temperature at the variousembedded couples to a given degree, the rate of conductivity may bedetermined. Other tests include those in muffles to determine the rateof expansion and the effect of heat and compressive stresses combined onthe compressive strength of the various structural materials. Themethods of making the panel tests, and the equipment used, are describedand illustrated in Bulletin No. 329, and the results of the tests havebeen published in detail. [10]

_Building Stones Investigations. _--The field investigations of buildingstones are conducted by Mr. E. F. Burchard, and include the examinationof the various deposits found throughout the United States. A study ofthe granites of New England has been commenced, which includes thecollection of type specimens of fine, medium, and coarse-grainedgranites, and of dark, medium, and light-gray or white granites. Acomparative series of these granites, consisting of prisms and cubes of4 and 2 in. , respectively, has been prepared. 

 [Illustration: Fig. 6. 

 PLAN OF LABORATORY FOR SALT-WATER TESTS AT ATLANTIC CITY, N. J. ]

The standard adopted for compressive test pieces in the 10, 000, 000-lb. Machine is a prism, having a base of 12 in. And being 24 in. High. Thetests include not only those for compression or crushing strength, butalso those for resistance to compressive strains of the prisms andcubes, when raised to high temperatures in muffles or kilns; resistanceto weathering, freezing, and thawing; porosity; fire-resistingqualities, etc. 

In collecting field samples, special attention is paid to the occurrenceof the stone, extent of the deposit, strike, dip, etc. , and specimensare procured having their faces cut with reference to the beddingplanes, in order that compressive and weathering tests may be made, notonly in relation to these planes but at those angles thereto in whichthe material is most frequently used commercially. Attention is alsopaid to the results of blasting, in its relation to compressive strains, as blasting is believed to have a material effect on stones, especiallyon those which may occur in the foundations of great masonry dams, andtype specimens of stone quarried by channeling, as well as by blasting, are collected and tested. 

_Clay and Clay Products Investigations. _--These investigations are incharge of Mr. A. V. Bleininger, and include the study of the occurrenceof clay beds in various parts of the United States, and the adaptabilityof each clay to the manufacture of the various clay products. 

Experiments on grinding, drying, and burning the materials are conductedat the Pittsburg testing station, to ascertain the most favorableconditions for preparing and burning each clay, and to determine themost suitable economic use to which it may be put, such as themanufacture of building or paving bricks, architectural tiles, sewertiles, etc. 

The laboratory is equipped with various grinding and drying devices, muffles, kilns, and apparatus for chemical investigations, physicaltests, and the manufacture and subsequent investigative tests of clayproducts. 

This section occupies the east end of Building No. 10, and rooms on thefirst and second floors have been allotted for this work. In addition, abrick structure, 46 by 30 ft. , provided with a 60-ft. Iron stack, hasbeen erected for housing the necessary kilns and furnaces. 

 [Illustration: PLATE XVI. 

 Fig. 1. --Brick Machine and Universal Cutter. 

 Fig. 2. --House-Heating Boilers, Building No. 21. ]

On the ground floor of Building No. 10, adjoining the cement andconcrete section, is a storage room for raw materials and product underinvestigation. Adjoining this room, and connecting with it by widedoors, is the grinding room, containing a 5-ft. Wet pan, with 2, 000-lb. Rollers, to be used for both dry and wet grinding. Later, a heavy drypan is to be installed. With these machines, even the hardest materialcan be easily disintegrated and prepared. In this room there is also ajaw crusher for reducing smaller quantities of very hard material, aswell as a 30 by 16-in. Iron ball mill, for fine grinding. These machinesare belted to a line shaft along the wall across the building. Amplesink drainage is provided for flushing and cleaning the wet pan, whenchanging from one clay to another. 

A large room adjoining is for the operation of all moulding and shapingmachines, representing the usual commercial processes. At present theseinclude an auger machine, with a rotary universal brick and tile cutter, Fig. 1, Plate XVI, and a set of brick and special dies, a hand repressfor paving brick, and a hand screw press for dry pressing. The brickmachine is operated from the main shaft which crosses the building inthis room and is driven from a 50-h. P. Motor. It is possible thus tostudy the power consumption under different loads and with differentclays, as well as with varying degrees of water content in the clay. Asthe needs of the work demand it, other types of machines are to beinstalled. For special tests in which pressure is an important factor itis intended to fit up one of the compression testing machines of thecement section with the necessary dies, thus enabling the pressing to becarried on under known pressures. Crushing, transverse, and other testsof clay products are made on the testing machines of the cement andconcrete laboratories. 

Outside of the building, in a lean-to, there is a double-chamber rattlerfor the testing of paving brick according to the specifications of theNational Brick Manufacturers’ Association. 

In the smaller room adjoining the machine laboratory there are two smallwet-grinding ball mills, of two and four jars, respectively, and also a9-leaf laboratory filter press. 

The remaining room on the first floor is devoted to the drying of claysand clay wares. The equipment consists of a large sheet-iron drying ovenof special construction, which permits of close regulation of thetemperature (Fig. 7). It is heated by gas burners, and is used for thepreliminary heat treatment of raw clays, in connection with the study ofthe drying problems of certain raw materials. It is intended to workwith temperatures as high as 250° cent. 

Another drying closet, heated by steam coils (Fig. 8), intended fordrying various clay products, has been designed with special referenceto the exact regulation of the temperature, humidity, and velocity ofthe air flowing through it. Both dryers connect by flues with an ironstack outside the building. This stack is provided with a suction fan, driven by a belt from an electric motor. 

On the second floor are the chemical, physical, and researchlaboratories, dealing with the precise manipulations of the tests andinvestigations. 

The chemical laboratory is fully equipped with the necessary apparatusfor carrying on special chemical research in silicate chemistry, including electrical resistance furnaces, shaking devices, etc. It isnot the intention to do routine work in this laboratory. The officeadjoins this laboratory, and near it is the physical laboratory, devotedto the study of the structure of raw materials. The latter containsNobel and Schoene elutriators, together with viscosimeters of the flowand the Coulomb and Clark electrical types, sieves, voluminometers, colorimeters, vernier shrinkage gauges, micrometers, microscopes, andthe necessary balances. 

The room across the hall is devoted to the study of the specificgravity, absorption, porosity, permeability, hardness, translucency, etc. , of burnt-clay products, all the necessary apparatus beingprovided. In the two remaining rooms, intended for research work, special apparatus adapted to the particular investigation may be set up. All the rooms are piped for water, gas, compressed air, steam, anddrainage, and wired for light and power. 

In the kiln house there is a test kiln adapted for solid fuel and gas. It is of the down-draft type, with an available burning space of about 8cu. Ft. (Fig. 9). For heavier ware and the study of the fire behavior ofclay products under conditions approaching those of practice, a rounddown-draft kiln, with an inside diameter of 6 ft. , is installed. About13 ft. Above the floor level, and supported by iron beams, there is aflue parallel to the long side of the structure. This flue conducts thegases of the kilns to the stack, which is symmetrically located withreference to the kiln house. Natural gas is the principal fuel. Inaddition to these kilns, a small muffle furnace, fired with petroleum, is provided for the determination of melting points, and an electriccarbon resistance furnace, with an aluminum muffle for high-temperaturework. For crucible-fusion work, a gas-fired pot furnace is installed. 

 [Illustration: Fig. 7. 

 CLAY-DRYING OVEN]

Along the north wall, bins are provided for the storage of fuel, clay, sand, and other kiln supplies. There are two floor drainage sinks, andelectric current, steam, water, and compressed air, are provided. 

 [Illustration: Fig. 8. 

 DRYING CLOSETS FOR CERAMICS]

_Results of the Work. _--More than 39, 300 separate test pieces have beenmade at the structural-materials testing laboratory. In connection withthe study of these, 86, 000 tests and nearly 14, 000 chemical analyseshave been made. Of these tests more than 13, 600 have been of theconstituent materials of concrete, including tensile tests of cementbriquettes, compression tests of cylinders and cubes, and transversetests of various specimens. 

Nearly 1, 200 beams of concrete or reinforced concrete, each 13 ft. Longand 8 by 11 in. In cross-section, have been made, and, in connectionwith the investigation of the behavior of these beams, nearly 3, 000tests have been made. Nearly 900 of these beams, probably more thandouble the entire number made in other laboratories in the UnitedStates, during a period of more than 15 years, have been tested. 

In the section of building blocks, 2, 200 blocks have been tested, including, with auxiliary pieces, more than 4, 500 tests; also, more than900 pieces of concrete have been tested for permeability and shear. Thephysical tests have numbered 14, 000; tests of steel for reinforcement, 3, 800; and 550 tests to determine fire-resistive qualities of variousbuilding materials, have been made on 30 special panels, and onmiscellaneous pieces. 

 [Illustration: Fig. 9. 

 DOWN-DRAFT KILN]

The tests of the permeability of cement mortars and concretes, and ofwater-proofing and damp-proofing materials, have numbered 3, 470. 

The results of the work of the Structural Materials Division havealready appeared in preliminary bulletins, as follows: No. 324, “SanFrancisco Earthquake and Fire of April 18, 1906, and Their Effects onStructures and Structural Materials”; No. 329, “Organization, Equipment, and Operation of the Structural-Materials Testing Laboratories at St. Louis, Mo. ”; No. 331, “Portland Cement Mortars and Their ConstituentMaterials” (based on nearly 25, 000 tests); No. 344, “Strength ofConcrete Beams” (based on tests of 108 beams); No. 370, “Fire-ResistiveProperties of Various Building Materials”; No. 387, “The Colloid Matterof Clay and its Measurements. ” A bulletin on the results of tests ofreinforced concrete beams, one on the manufacture and chemistry of lime, and one on drying tests of brick, are in course of publication. 

FUEL INVESTIGATIONS. 

The scope of the fuel investigations has been planned to conform to theprovisions of the Act of Congress which provides for analyzing andtesting coals, lignites, and other mineral fuel substances belonging tothe United States, or for the use of the United States Government, andexaminations for the purpose of increasing the general efficiency oravailable supply of the fuel resources in the United States. 

In conformity with this plan, the investigations inaugurated at St. Louis had for their initial object the analyzing and testing of thecoals of the United States, using in this work samples of from 1 to 3carloads, collected with great care from typical localities in the moreimportant coal fields of the country, with a view to determining therelative values of those different fuels. In the work at Norfolk, during1907, this purpose was modified to the extent of keeping in viewrelative fuel efficiencies for naval purposes. The tests at Denver havebeen on coal from Government land or from land contiguous thereto, andare conducted solely with a view to perfecting methods of coking thiscoal by prior washing and by manipulation in the process of coking. 

Three general lines of inquiry are embodied in the plan of investigationundertaken and contemplated by the Technologic Branch, after conferenceand with the advice and approval of the Advisory Board: 1. Theascertainment of the best mode of utilizing any fuel deposit owned or tobe used by the Government, or the fuel of any extensive deposit as awhole, by conducting a more thorough investigation into its combustionunder steam boilers, conversion into producer gas, or into coke, briquettes, etc. 2. The prevention of waste, through the study of thepossibility of improvement in the methods of mining, shipping, utilizing, etc. 3. The inspection and analysis of coal and lignitepurchased under specification for the use of the Government, toascertain its heating value, ash, contained moisture, etc. 

The first general line of work concerns the investigation and testing ofthe fuel resources of the United States, and especially those belongingto the Federal Government, to determine a more efficient and moreeconomical method of utilizing the same. This work has developed alongthe following lines:

The collection of representative samples for chemical analysis, andcalorimeter tests by a corps of skilled mine samplers, from the minesselected as typical of extensive deposits of coal in a given field orfrom a given bed of coal; and the collection from the same mines oflarger samples of from 1 to 3 carloads, shipped to the testing stationfor tests in boiler furnaces, gas producers, etc. , as a check on theanalysis and calorimeter tests;

The testing of each coal received to determine the most efficient andleast wasteful method of use in different furnaces suitable for publicbuildings or power plants or ships of the Government;

The testing of other portions of the same shipment of coal in the gasproducer, for continuous runs during periods of a few days up to severalweeks, in order to determine the availability of this fuel for use insuch producers, and the best method of handling it, to determine theconditions requisite to produce the largest amount of high-grade gasavailable for power purposes;

The testing of another portion of the same coal in a briquette machineat different pressures and with different percentages and kinds ofbinder, in order to determine the feasibility of briquetting the slackor fine coal. Combustion tests are then made of these briquettes, todetermine the conditions under which they may be burned advantageously;

Demonstrations, on a commercial scale, of the possibility of producingbriquettes from American lignites, and the relative value of these forpurposes of combustion as compared with the run-of-mine coal from whichthe briquettes are made;

The finding of cheaper binders for use in briquetting friable coals notsuited for coking purposes;

Investigations into the distribution, chemical composition, andcalorific value of the peat deposits available in those portions of theUnited States where coal is not found, and the preparation of such peatfor combustion, by drying or briquetting, to render it useful as a localsubstitute for coal;

Investigations into the character of the various petroleums foundthroughout the United States, with a view to determining their calorificvalue, chemical composition, and the various methods whereby they may bemade most economically available for more efficient use as powerproducers, through the various methods of combustion;

Investigations and tests into the relative efficiency, as powerproducers in internal-combustion engines, of the heavier distillates ofpetroleum, as well as of kerosene and gasoline, in order to ascertainthe commercial value and relative efficiency of each product in thevarious types of engines;

Investigations into the most efficient methods of utilizing the variouscoals available throughout the United States for heating small publicbuildings, army posts, etc. , in order that these coals may be used moreeconomically than at present;

Investigative studies into the processes of combustion within boilerfurnaces and gas producers to ascertain the temperatures at which themost complete combustion of the gases takes place, and the means wherebysuch temperatures may be produced and maintained, thus diminishing theloss of values up the smokestack and the amount of smoke produced;

Investigations and tests into the possibilities of coking coals whichhave hitherto been classed as non-coking, and the making of comparativetests of all coals found in the United States, especially those from thepublic lands of the West;

Investigations, by means of washing in suitable machines, to determinethe possibility of improving the quality of American coals for variousmethods of combustion, and with a view to making them more available forthe production of coke of high-grade metallurgical value, as free aspossible from sulphur and other injurious substances. 

At each stage of the process of testing, samples of the coal have beenforwarded to the chemical laboratory for analyses; combustiontemperatures have been measured; and samples of gas collected fromvarious parts of the combustion chambers of the gas producers and boilerfurnaces have been analyzed, in order that a study of these data maythrow such light on the processes of combustion and indicate suchnecessary changes in the apparatus, as might result in larger economiesin the use of coal. 

The second line of investigation concerns the methods of mining andpreparing coal for the market, and the collection of mine samples ofcoal, oil, etc. , for analysis and testing. It is well known that, underpresent methods of mining, from 10 to 75% of any given deposit of coalis left underground as props and supports, or as low-grade material, orin overlying beds broken up through mining the lower bed first. Anaverage of 50% of the coal is thus wasted or rendered valueless, as itcannot be removed subsequently because of the caving or falling in ofthe roofs of abandoned galleries and the breaking up of the adjoiningoverlying beds, including coal, floor, and roof. 

The investigations into waste in mining and the testing of the waste, bone, and slack coal in gas producers, as briquettes, etc. , have, fortheir purpose, the prevention of this form of waste by demonstratingthat these materials, now wasted, may be used profitably, by means ofgas producers and engines, for power purposes. 

The third general line of investigation concerns the inspection andsampling of fuel delivered to the Government under purchase contracts, and the analyzing and testing of the samples collected, to determinetheir heating value and the extent to which they may or may not complywith the specifications under which they are purchased. The coaldelivered at the public buildings in the District of Columbia is sampledby special representatives of the Technologic Branch of the Survey. Thetaking of similar samples at public buildings and posts throughout theUnited States, and the shipment of the samples in hermetically sealedcans or jars to the chemical laboratory at Washington, is for the mostpart looked after by special officers or employees at each place. Thesepurchases are made, to an increasing extent, under specifications whichprovide premiums for coal delivered in excess of standards, andpenalties for deliveries below standards fixed in the specifications. The standard for bituminous coals is based mainly on the heat units, ash, and sulphur, while that for anthracite coal is based mainly on thepercentage of ash and the heat units. 

In connection with all these lines of fuel testing, certain researchwork, both chemical and physical, is carried on to determine the truecomposition and properties of the different varieties of coal, thechanges in the transformation from peat to lignite, from lignite tobituminous coal, and from bituminous to anthracite coal, and thechemical and physical processes in combustion. Experiments are conductedconcerning the destructive distillation of fuels; the by-products ofcoking processes; the spontaneous combustion of coal; the storage ofcoal, and the loss in value in various methods of storing; and kindredquestions, such as the weathering of coal. These experiments may yieldvaluable results through careful chemical research work supplemented byequally careful observations in the field. 

_Inspection and Mine Sampling. _--In the Geological Survey Building, atWashington, coal purchased for Government use on a guaranteed-analysisor heat-value basis, is inspected and sampled. 

Some of the employees on this work are constantly at the mines takingsamples, or at public works inspecting coal for Government use, whileothers are stationed at Washington to look after the deliveries of coalto the many public buildings, and to collect and prepare samples takenfrom these deliveries for analysis, as well as to prepare samplesreceived from public works and buildings in other parts of the country. 

 [Illustration: Fig. 10. 

 COAL-SAMPLING ROOM, GEOLOGICAL SURVEY, WASHINGTON, D. C. ]

The preparation of these samples is carried on in a room in the basementof the building, where special machinery has been installed for thiswork. Fig. 10 shows a plan of this room and the arrangement of thesampling and crushing machinery. 

The crushing of the coal produces great quantities of objectionabledust, and to prevent this dust from giving trouble outside the samplingroom, the wooden partitions on three sides of the room (the fourth sidebeing a masonry wall) are completely covered on the outside withgalvanized sheet iron. The only openings to the room are two doors, which are likewise covered with sheet iron, and provided with broadflanges of the same material, in order to seal effectually the openingswhen the doors are shut. Fresh air is drawn into the room by a fan, through a pipe leading to the outer air. A dust-collecting system whichcarries the coal dust and spent air from the room, consists of anarrangement of 8-in. And 12-in. Pipes leading from hoods, placed overthe crushing machines, to the main furnace stack of the building. Thedraft in this stack draws all the dust from the crushers directlythrough the hoods to the main pipe, where most of it is deposited. 

The equipment of the sampling room consists of one motor-driven, babyhammer crusher, which has a capacity of about 1 ton per hour and crushesto a fineness of ¼-in. Mesh; one adjustable chipmunk jaw crusher, for 5-and 10-lb. Samples; one set of 4½ by 7½-in. Rolls, crushing to 60 mesh, for small samples; one large bucking board, and several different sizesof riffle samplers for reducing samples to small quantities. The smallcrushers are belted to a shaft driven by a separate motor from thatdriving the baby crusher. 

In conducting the inspection of departmental purchases of coal inWashington, the office is notified whenever a delivery of coal is to bemade at one of the buildings, and an inspector is sent, who remainsduring the unloading of the coal. He is provided with galvanized-ironbuckets having lids and locks; each bucket holds about 60 lb. Of coal. In these buckets he puts small quantities of the coal taken from everyportion of the delivery, and when the delivery has been completed, helocks the buckets and notifies the office to send a wagon for them. Thebuckets are numbered consecutively, and the inspector makes a record ofthese numbers, the date, point of delivery, quality of coal delivered, etc. The buckets are also tagged to prevent error. He then reports tothe office in person, or by telephone, for assignment to another pointin the city. All the samples are delivered to the crushing room in thebasement of the Survey Building, to be prepared for analysis. [11]

Samples taken from coal delivered to points outside of Washington aretaken by representatives of the department for which the coal is beingpurchased, according to instructions furnished them, and, from time totime, the regular inspectors are sent to see that these instructions arebeing complied with. These samples are crushed by hand, reduced to about2 lb. At the point where they are taken, and sent to Washington, inproper air-tight containers, by mail or express, accompanied byappropriate descriptions. 

Each sample is entered in the sample record book when received, and isgiven a serial number. For each contract a card is provided givinginformation relative to the contract. On this card is also entered theserial number of each sample of coal delivered under that contract. 

After the samples are recorded, they are sent to the crushing room, where they are reduced to the proper bulk and fineness for analysis. They are then sent, in rubber-stoppered bottles, accompanied by blankanalysis report cards and card receipts, one for each sample, showingthe serial numbers, to the fuel laboratory for analysis. The receiptcard for each sample is signed and returned to the inspection office, and when the analysis has been made, the analysis report card showingthe result is returned. This result is entered at once on the contractcard, and when all analyses have been received, covering the entiredelivery of coal, the average quality is calculated, and the results arereported to the proper department. 

The matter of supplying the Pittsburg plant with fuel for test purposesis also carried on from the Washington office. Preliminary to a seriesof investigations, the kinds and amounts of coal required are decidedon, and the localities from which these coals are to be obtained aredetermined. Negotiations are then opened with the mine owners, who, inmost cases, generously donate the coal. When the preliminaries have beenarranged, an inspector is sent to the mine to supervise the loading andshipment of the coal. This inspector enters the mine and takes, forchemical analysis, small mine samples which are sent to the laboratoryat Pittsburg in metal cans by mail, accompanied by proper identificationcards. The results of the analysis are furnished to the experts incharge at the testing plant, for their information and guidance in theinvestigations for which the coal was shipped. 

All samples for testing purposes are designated consecutively in theorder of shipment, “Pittsburg No. 1, ” “Pittsburg No. 2, ” etc. A completerecord of all shipments is kept on card forms at the Pittsburg plant, and a duplicate set of these is on file in the inspection office atWashington. 

_Analysis of Fuels. _--The routine analyses of fuel used in thecombustion tests at Pittsburg, and of the gases resulting fromcombustion or from explosions in the testing galleries, or sampled inthe mines, are made in Building No. 21. [12] A small laboratory is alsomaintained on the second floor of the south end of Building No. 13, foranalyses of gases resulting from combustion in the producer-gas plant, and from explosions in Galleries Nos. 1 and 2, etc. From four to sixchemists are continually employed in this laboratory (in 8-hour shifts), during prolonged gas-producer tests, and three chemists are alsoemployed in analyzing gases relating to mine explosions. 

In addition to these gas analyses, there are also made in the mainlaboratory, analyses and calorific tests of all coal samples collectedby the Geological Survey in connection with its land-classification workon the coal lands of the Western States. Routine analyses of mine, car, and furnace samples of fuels for testing, before and after washing andbriquetting, before coking and the resultant coke, and extractionanalyses of binders for briquettes, etc. , are also made in thislaboratory. 

The fuel-testing laboratory at Washington is equipped with three Mahlerbomb calorimeters and the necessary balances and chemical equipmentrequired in the proximate analysis of coal. More than 650 deliveries ofcoal are sampled each month for tests, representing 50, 000 tonspurchased per month, besides daily deliveries, on ship-board, of 550, 000tons of coal for the Panama Railroad. The data obtained by these testsfurnish the basis for payment. The tests cover deliveries of coal to theforty odd bureaus, and to the District Municipal buildings inWashington; to the arsenals at Watertown, Mass. , Frankford, Pa. , andRock Island, Ill. ; and to a number of navy yards, through the Bureau ofYards and Docks; to military posts in various parts of the country; forthe Quartermaster-General’s Department; to the Reclamation Service; toIndian Agencies and Soldiers’ Homes; to several lighthouse districts;and to the superintendents of the various public buildings throughoutthe United States, through the Treasury Department; etc. During 1909, the average rate of reporting fuel samples was 540 per month, requiring, on an average, six determinations per sample, or about 3, 240determinations per month. 

_Fuel-Research Laboratories. _--Smaller laboratories, occupying, on theaverage, three rooms each, are located in Building No. 21. One is usedfor chemical investigations and calorific tests of petroleum collectedfrom the various oil fields of the United States; another is used forinvestigations relative to the extraction of coal and the rapidity ofoxidization of coals by standard solutions of oxidizing agents; andanother is occupied with investigations into the destructivedistillation of coal. The researches under way show the wide variationin chemical composition and calorific value of the various crude oils, indicate the possibility of the extraction of coal constituents bysolvents, and point to important results relative to the equilibrium ofgases at high temperatures in furnaces and gas producers. Theinvestigations also bear directly on the coking processes, especiallythe by-product process, as showing the varying proportion of each of thevolatile products derivable from types of coals occurring in the variouscoal fields of the United States, the time and temperature at whichthese distillates are given off, the variation in quality and quantityof the products, according to the conditions of temperature, and, inaddition, explain the deterioration of coals in storage, etc. 

 [Illustration: Fig. 11. 

 PLAN OF CONSTRUCTION DETAILS OF METAL HOOD]

At the Washington office, microscopic investigations into the lifehistory of coal, lignite, and peat are being conducted. Theseinvestigations have already progressed far enough to admit of theidentification of some of the botanical constituents of the older peatsand the younger lignites, and it is believed that the origin of theolder lignites, and even of some of the more recent bituminous coals, may be developed through this examination. 

In the chemical laboratories, in Building No. 21, the hoods (Figs. 11and 12) are of iron, with a brick pan underneath. They are supported oniron pipes, as are most of the other fixtures in the laboratories inthis building. The hood proper is of japanned, pressed-iron plate, No. 22 gauge, the same material being used for the boxes, slides, and bottomsurrounding the hood. The sash is hung on red copper pulleys, and thecorners of the hood are reinforced with pressed, japanned, riveted plateto which the ventilating pipe is riveted. 

 [Illustration: Fig. 12. 

 ELEVATION OF CONSTRUCTION DETAILS OF METAL HOOD]

There is some variety in the cupboards and tables provided in thevarious laboratories, but, in general, they follow the design shown inFig. 13. The table tops, 12 ft. Long, are of clear maple in full-lengthpieces, ⅞ in. Thick and 2⅝ in. Wide, laid on edge and drilled at18-in. Intervals for bolts. These pieces are glued and drawn together bythe bolts, the heads of which are countersunk. The tops, planed off, sanded, and rounded, are supported on pipe legs and frames of 1¼ by1½-in. Galvanized-iron pipe with screw flanges fitting to the floor andtop. Under the tops are drawers and above them re-agent shelves. Halfwaybetween the table top and the floor is a wire shelf of a frame-work ofNo. 2 wire interlaced with No. 12 weave of ⅝-in. Square mesh. 

Certain of the tables used in the laboratory are fitted with cupboardsbeneath and with drawers, and, in place of re-agent stands, porcelain-lined sinks are sunk into them. These tables follow, ingeneral style and construction, the re-agent tables. The tables used inconnection with calorimeter determinations are illustrated in Fig. 14. The sinks provided throughout these laboratories are of standardporcelain enamel, rolled rim, 18 by 13 in. , with enameled back, over asink and drain board, 24 in. Long on the left side, though there arevariations from this type in some instances. 

The plumbing includes separate lines of pipe to each hood and table; oneeach for cold water, steam at from 5 to 10 lb. Pressure, compressed air, natural gas, and, in some cases, live steam at a pressure of 60 lb. 

On each table is an exposed drainage system of 2½-in. Galvanized-ironpipe, in the upper surface of which holes have been bored, through whichthe various apparatus drain by means of flexible connections of glass orrubber. These pipes and the sinks, etc. , discharge into main drains, hung to the ceiling of the floor beneath. These drains are of wood, asphaltum coated, with an inside diameter ranging from 3 to 6 in. , andat the proper grades to secure free discharge. These wooden drain-pipesare made in short lengths, strengthened by a spiral wrapping of metalbands, and are tested to a pressure of 40 lb. Per sq. In. Angles areturned and branches connected in 4- and 6-in. Square headers. 

 [Illustration: Fig. 13. 

 PLAN OF CONSTRUCTION DETAILS OF REAGENT TABLES BUILDING 21. ]

 [Illustration: Fig. 14. 

 CONSTRUCTION DETAILS OF CALORIMETER TABLES]

The entire building is ventilated by a force or blower fan in thebasement, and by an exhaust fan in the attic with sufficient capacity toinsure complete renewal of air in each laboratory once in 20 min. 

The blower fan is placed in the center of the building, on the groundfloor, and is 100 in. In diameter. Its capacity is about 30, 000 cu. Ft. Of air per min. , and it forces the air, through a series of pipes, intoregisters placed in each of the laboratories. 

The exhaust fan, in the center of the attic, is run at 550 rev. Permin. , and has a capacity of 22, 600 cu. Ft. Of air per min. It draws theair from each of the rooms below, as well as from the hoods, through amain pipe, 48 in. In diameter. 

_Steaming and Combustion Tests. _--The investigations included under theterm, fuel efficiency, relate to the utilization of the various types offuels found in the coal and oil fields, and deal primarily with thecombustion of such fuels in gas producers, in the furnaces of steamboilers, in locomotives, etc. , and with the efficiency and utilizationof petroleum, kerosene, gasoline, etc. , in internal-combustion engines. This work is under the general direction of Mr. R. L. Fernald, and isconducted principally in Buildings Nos. 13 (Plate XVII) and 21. 

For tests of combustion of fuels purchased by the Government, theequipment consists of two Heine, water-tube boilers, each of 210 h. P. , set in Building No. 13. One of these boilers is equipped with a Jonesunderfeed stoker, and is baffled in the regular way. At four points inthe setting, large pipes have been built into the brick wall, to permitmaking observations on the temperature of the gas, and to take samplesof the gas for chemical analysis. 

The other boiler is set with a plain hand-fired grate. It is baffled togive an extra passage for the gases (Fig. 15). Through the side of thisboiler, at the rear end, the gases from the long combustion chamber(Plate XVIII) enter and take the same course as those from thehand-fired grate. Both the hand-fired grate and the long combustionchamber may be operated at the same time, but it is expected thatusually only one will be in operation. A forced-draft fan has beeninstalled at one side of the hand-fired boiler, to provide air pressurewhen coal is being burned at high capacity. This fan is also connectedin such a way as to furnish air for the long combustion chamber whendesired. A more complete description of the boilers may be found inProfessional Paper No. 48, and Bulletin No. 325 of the U. S. GeologicalSurvey, in which the water-measuring apparatus is also described. [13]

On account of the distance from Building No. 21 to the main group ofbuildings, it was considered inadvisable to attempt to furnish steamfrom Building No. 13 to Building No. 21, either for heating or powerpurposes. In view, moreover, of the necessity of installing varioustypes and sizes of house-heating boilers, on account of tests to be madethereon in connection with these investigations, it was decided toinstall these boilers in the lower floor of Building No. 21, where theycould be utilized, not only in making the necessary tests, but infurnishing heat and steam for the building and the chemical laboratoriestherein. 

 [Illustration: Fig. 15. 

 SETTING FOR 210-HORSE POWER, HAND-FIRED BOILERS]

In addition to the physical laboratory on the lower floor of BuildingNo. 21, and the house-heating boiler plant with the necessary coalstorage, there are rooms devoted to the storage of heavy supplies, samples of fuels and oils, and miscellaneous commercial apparatus. Oneroom is occupied by the ventilating fan and one is used for thenecessary crushers, rolls, sizing screens, etc. , required in connectionwith the sampling of coal prior to analysis. 

The Quartermaster’s Department having expressed a wish that tests bemade of the heating value and efficiency of the various fuels offeredthat Department, in connection with the heating of military poststhroughout the country, three house-heating boilers were procured whichrepresent, in a general way, the types and sizes used in a medium-sizedhospital or other similar building, and in smaller residences (Fig. 2, Plate XVI). The larger apparatus is a horizontal return-tubular boiler, 60 in. In diameter, 16 ft. Long, and having fifty-four 4-in. Tubes. [14]

In order to determine whether such a boiler may be operated underheating conditions without making smoke, when burning various kinds ofcoal, it has been installed in accordance with accepted ideas regardingthe prevention of smoke. A fire-brick arch extends over the entire gratesurface and past the bridge wall. A baffle wall has been built in thecombustion chamber, which compels the gases to pass downward and todivide through two openings before they reach the boiler shell. Provision has been made for the admission of air at the front of thefurnace, underneath the arch, and at the rear end of the bridge wall, thus furnishing air both above and below the fire. It is not expectedthat all coals can be burned without smoke in this furnace, but it isdesirable to determine under what conditions some kinds of coals may beburned without objectionable smoke. [15]

For sampling the gases in the smokebox of the horizontal return-tubularboiler, a special flue-gas sampler was designed, in order to obtain acomposite sample of the gases escaping from the boiler. 

The other heaters are two cast-iron house-heating boilers. One cansupply 400 sq. Ft. Of radiation and the other about 4, 000 sq. Ft. Theywere installed primarily for the purpose of testing coals to determinetheir relative value when burned for heating purposes. They are piped toa specially designed separator, and from this to a pressure-reducingvalve. Beyond this valve an orifice allows the steam to escape into theregular heating mains. This arrangement makes it possible to maintain apractically constant load on the boilers. 

 [Illustration: PLATE XVIII. 

 Fig. 1. --Long Combustion Chamber. 

 Fig. 2. --Gas Sampling Apparatus, Long Combustion Chamber. ]

There is a fourth boiler, designed and built for testing purposes by theQuartermaster’s Department. This is a tubular boiler designed on thelines of a house-heating boiler, but for use as a calorimeter todetermine the relative heat value of different fuels reduced to thebasis of a standard cord of oak wood. 

A series of research tests on the processes of combustion is beingconducted in Building No. 13, by Mr. Henry Kreisinger. These tests arebeing made chiefly in a long combustion chamber (Figs. 16 and 17, andFigs. 1 and 2, Plate XVIII), which is fed with coal from a Murphymechanical stoker, and discharges the hot gases at the rear end of thecombustion chamber, into the hand-fired Heine boiler. The walls and roofof this chamber are double; the inner wall is 9 in. Thick, offire-brick; the outer one is 8 in. Thick, and is faced with red pressedbrick. Between the walls of the sides there is a 2-in. Air space, andbetween them on the roof a 1-in. Layer of asbestos paste is placed. Theinner walls and roof have three special slip-joints, to allow forexpansion. The floor is of concrete, protected by a 1½-in. Layer ofasbestos board, which in turn is covered by a 3-in. Layer of earth; ontop of this earth there is a 4-in. Layer of fire-brick (not shown in thedrawings). 

 [Illustration: Fig. 16. 

 CROSS-SECTIONS OF CHAMBER AND OF FURNACE, LONG COMBUSTION CHAMBER]

Inasmuch as one of the first problems to be attacked will be thedetermination of the length of travel and the time required to completecombustion in a flame in which the lines of stream flow are nearlyparallel, great care was taken to make the inner surfaces of the tunnelsmooth, and all corners and hollows are rounded out in the direction oftravel of the gases. 

Provision is made, by large peep-holes in the sides, and by smallersampling holes in the top, for observing the fuel bed at several pointsand also the flame at 5-ft. Intervals along the tunnel. Temperatures andgas samples are taken simultaneously at a number of points through theseholes, so as to determine, if possible, the progress of combustion(Fig. 1, Plate XVIII). 

About twenty thermo-couples are embedded in the walls, roof, and floor, some within 1 in. Of the inside edge of the tunnel walls, and some inthe red pressed brick near the outer surface, the object of which is toprocure data on heat conduction through well-built brick walls[16] (Fig. 2, Plate XVIII). 

In order to minimize the leakage of air through the brickwork, thefurnace and tunnel are kept as nearly as possible at atmosphericpressure by the combined use of pressure and exhausting fans. Nevertheless, the leakage is determined periodically as accurately aspossible. 

At first a number of tests were run to calibrate the apparatus as awhole, all these preliminary tests being made on cheap, carefullyinspected, uniform screenings from the same seam of the same mine nearPittsburg. Later tests will be run with other coals of various volatilecontents and various distillation properties. 

It is anticipated that the progress of the tests may suggest changes inthe construction or operation of this chamber. It is especiallycontemplated that the section of the chamber may be narrowed down bylaying sand in the bottom and fire-brick thereon; also that baffle wallsmay be built into various portions of it, and that cooling surfaces withbaffling may be introduced. In addition to variations in the tests, dueto changes in construction in the combustion chamber, there will bevariations in the fuels tested. Especial effort will be made to procurefuels ranging in volatile content from 15 to 27 and to 40%, and thosehigh in tar and heavy hydro-carbons. It is also proposed to vary theconditions of testing by burning at high rates, such as at 15, 20, and30 lb. Per ft. Of grate surface, and even higher. Records will be keptof the weight of coal fired and of each firing, of the weight of ash, etc. ; samples of coal and of ash will be taken for chemical and physicalanalysis, as well as samples of the gas, and other essential data. Theserecords will be studied in detail. 

 [Illustration: Fig. 17. 

 LONGITUDINAL SECTIONS OF LONG COMBUSTION CHAMBER]

A series of heat-transmission tests undertaken two years ago, is beingcontinued on the ground floor of Building No. 21, on modified apparatusreconstructed in the light of the earlier experiments by Mr. W. T. Ray. The purpose of the tests on this apparatus has been to determine some ofthe laws controlling the rate of transmission of heat from a hot gas toa liquid and _vice versa_, the two being on the opposite sides of ametal tube. 

It appears that four factors determine the rate of heat impartation fromthe gas to any small area of the metal[17]:

 [Footnote 17: The assumption is made that a metal tube free from scale will remain almost as cool as the water; actual measurements with thermo-couples have indicated the correctness of this assumption in the majority of cases. ]

 (1). --The temperature difference between the body of the gas and the metal;

 (2). --The weight of the gas per cubic foot, which is proportional to the number of molecules in any unit of volume;

 (3). --The bodily velocity of the motion of the gas parallel to any small area under consideration; and (probably), (4). --The specific heat of the gas at constant pressure. 

The apparatus consists of an electric resistance furnace containingcoils of nickel wire, a small (interchangeable) multi-tubular boiler, and a steam-jet apparatus for reducing the air pressure at the exit end, so as to cause a flow of air through the boiler. A surface condenser wasattached to the boiler’s steam outlet, the condensed steam being weighedas a check on the feed-water measurements. A number of thermometers andthermo-couples were used to obtain atmospheric-air temperature, temperatures of the air entering and leaving the boilers, and feed-watertemperature. 

The apparatus is now being reconstructed with appliances for measuringthe quantity of air entering the furnace, and an automaticelectric-furnace temperature regulator. 

 [Illustration: PLATE XIX. 

 Fig. 1. --Gas Producer, Economizer, and Wet Scrubber. 

 Fig. 2. --Producer Gas: Dry Scrubber and Gas Holder. ]

Three sizes of boiler have been tested thus far, the dimensions being asgiven in Table 4. 

Each of the three boilers was tested at several temperatures of enteringair, up to 1, 500° Fahr. , about ten tests being made at each temperature. It is also the intention to run, on these three boilers, about eighttests at temperatures of 1, 800°, 2, 100° and 2, 400° Fahr. , respectively. A bulletin on the work already done, together with much incidentalmatter, is in course of preparation. [18]

 TABLE 4. --Dimensions of Boilers Nos. 1, 2, and 3. 

 ------------------------------------+--------+--------+-------- Items. | Boiler | Boiler | Boiler | No. 1. | No. 2. | No. 3. ------------------------------------+--------+--------+-------- Distance, outside to outside of | | | boiler heads, in inches | 8. 28 | 8. 28 | 16. 125 Actual outside diameter of flues, | 0. 252 | 0. 313 | 0. 252 in inches | | | Actual inside diameter of flues, | 0. 175 | 0. 230 | 0. 175 in inches | | | Number of flues (tubes) | 10 | 10 | 10 ------------------------------------+--------+--------+--------

The work on the first three boilers is only a beginning; preparationsare being made to test eight more multi-tubular boilers of variouslengths and tube diameters, under similar conditions. Because of theexperience already obtained, it will be necessary to make only eighttests at each initial air temperature. 

When the work on multi-tubular boilers is completed, water-tube boilerswill be taken up, for which a fairly complete outline has been prepared. This second or water-tube portion of the investigation is really of thegreater scientific and commercial interest, but the multi-tubularboilers were investigated first because the mathematical treatment ismuch simpler. 

_Producer-Gas Tests. _--The producer-gas plant at the Pittsburg testingstation is in charge of Mr. Carl D. Smith, and has been installed forthe purpose of testing low-grade fuel, bone coal, roof coal, minerefuse, and such material as is usually considered of little value, oreven worthless for power purposes. The gas engine, gas producer, economizer, wet scrubber (Fig. 1, Plate XIX), and accessories, are inBuilding No. 13, and the dry scrubber, gas-holder, and water-coolingapparatus are immediately outside that building (Fig. 2, Plate XIX). 

At present immense quantities of fuel are left at the mines, in the formof culm and slack, which, in quality, are much below the average output. Such fuel is considered of little or no value, chiefly because there isno apparatus in general use which can burn it to good advantage. Theheat value of this fuel is often from 50 to 75% of that of the fuelmarketed, and if not utilized, represents an immense waste of naturalresources. Large quantities of low-grade fuel are also left in themines, simply because present conditions do not warrant its extraction, and it is left in such a way that it will be very difficult, if notpractically impossible, for future generations to take out such fuelwhen it will be at a premium. Again, there are large deposits oflow-grade coal in regions far remote from the sources of the presentfuel supply, but where its successful and economic utilization would bea boon to the community and a material advantage to the country atlarge. The great importance of the successful utilization of low-gradefuel is obvious. Until within very recent years little had beenaccomplished along these lines, and there was little hope of ever beingable to use these fuels successfully. 

The development of the gas producer for the utilization of ordinaryfuels, [19] however, indicates that the successful utilization ofpractically all low-grade fuel is well within the range of possibility. It is notable that, although all producer-gas tests at the Governmenttesting stations, at St. Louis and Norfolk, were made in a type ofproducer[20] designed primarily for a good grade of anthracite coal, thefuels tested included a wide range of bituminous coals and lignites, andeven peat and bone coal, and that, in nearly every test, little seriousdifficulty was encountered in maintaining satisfactory operatingconditions. [21] It is interesting to note that in one test, a bone coalcontaining more than 45% of ash was easily handled in the producer, andthat practically full load was maintained for the regulation test periodof 50 hours. [22]

It is not expected that all the fuels tested will prove to be ofimmediate commercial value, but it is hoped that much light will bethrown on this important problem. 

 [Illustration: PLATE XX. 

 Fig. 1. --Charging Floor of Gas Producer. 

 Fig. 2. --European and American Briquettes. ]

The equipment for this work consists of a single gas generator, rated at150 h. P. , and a three-cylinder, vertical gas engine of the samecapacity. The producer is a Loomis-Pettibone, down-draft, made by thePower and Mining Machinery Company, of Cudahy, Wis. , and is known as its“Type C” plant. The gas generator consists of a cylindrical shell, 6 ft. In diameter, carefully lined with fire-brick, and having an internaldiameter of approximately 4 ft. Near the bottom of the generator thereis a fire-brick grate, on which the fuel bed rests. The fuel is chargedat the top of the producer through a door (Fig. 1, Plate XX), which maybe left open a considerable time without affecting the operation of theproducer, thus enabling the operator to watch and control the fuel bedwith little inconvenience. As the gas is generated, it passes downwardthrough the hot fuel bed and through the fire-brick grate. Thisdown-draft feature “fixes, ” or makes into permanent gases, the tarryvapors which are distilled from bituminous coal when it is first chargedinto the producer. A motor-driven exhauster with a capacity of 375 cu. Ft. Per min. , draws the hot gas from the base of the producer through aneconomizer, where the sensible heat of the gas is used to pre-heat theair and to form the water vapor necessary for the operation of theproducer. The pre-heated air and vapor leave the economizer and enterthe producer through a passageway near the top and above the fuel bed. From the economizer the gas is drawn through a wet scrubber where itundergoes a further cooling and is cleansed of dirt and dust. Afterpassing the wet scrubber, the gas, under a light pressure, is forced, bythe exhauster, through a dry scrubber to a gas-holder with a capacity ofabout 1, 000 cu. Ft. 

All the fuel used is carefully weighed on scales which are checked fromtime to time by standard weights; and, as the fuel is charged into theproducer, a sample is taken for chemical analysis and for thedetermination of its calorific power. The water required for thegeneration of the vapor is supplied from a small tank carefullygraduated to pounds; this observation is made and recorded every hour. All the water used in the wet scrubber is measured by passing it througha piston-type water meter, which is calibrated from time to time toinsure a fair degree of accuracy in the measurement. Provision is madefor observing the pressure and temperature of the gas at various points;these are observed and recorded every hour. 

From the holder the gas passes through a large meter to the verticalthree-cylinder Westinghouse engine, which is connected by a belt to a175-kw. , direct-current generator. The load on the generator is measuredby carefully calibrated switch-board instruments, and is regulated by aspecially constructed water rheostat which stands in front of thebuilding. 

Careful notes are kept of the engine operation; the gas consumption andthe load on the engine are observed and recorded every 20 min. ; thequantity of jacket water used on the gas engine, and also itstemperature entering and leaving the engine jackets, are recorded everyhour. Indicator cards are taken every 2 hours. The work is continuous, and each day is divided into three shifts of 8 hours each; the length ofa test, however, is determined very largely by the character andbehavior of the fuel used. 

A preliminary study of the relative efficiency of the coals found indifferent portions of the United States, as producers of illuminatinggas, has been nearly completed under the direction of Mr. Alfred H. White, and a bulletin setting forth the results is in press. [23]

_Tests of Liquid Fuels. _--Tests of liquid fuels in internal-combustionengines, in charge of Mr. R. M. Strong, are conducted in the engine-roomof Building No. 13. 

The various liquid hydro-carbon fuels used in internal-combustionengines for producing power, range from the light refined oils, such asnaphtha, to the crude petroleums, and have a correspondingly widevariation of physical and chemical properties. 

The most satisfactory of the liquid fuels for use in internal-combustionengines, are alcohol and the light refined hydro-carbon oils, such asgasoline. These fuels, however, are the most expensive in commercialuse, even when consumed with the highest practical efficiency, which, itis thought, has already been attained, as far as present types ofengines are concerned. 

At present little is known as to how far many of the very cheapdistillates and crude petroleums can be used as fuel forinternal-combustion engines. It is difficult to use them at all, regardless of efficiency. 

Gasoline is comparatively constant in quality, and can be used withequal efficiency in any gasoline engine of the better grade. There aremany makes of high-grade gasoline engines, tests on any of which may betaken as representative of the performance and action of gasoline in aninternal-combustion engine, if the conditions under which the tests weremade are clearly stated and are similar. 

Kerosene varies widely in quality, and requires special devices for itsuse, but is a little cheaper than gasoline. It is possible that thekerosene engine may be developed so as to permit it to take the place ofthe smaller stationary and marine gasoline engines. This would meanconsiderable saving in fuel cost to the small power user, who now findsthe liquid-fuel internal-combustion engine of commercial advantage. Anumber of engines at present on the market use kerosene; some use onlythe lighter grades and are at best comparatively less efficient thangasoline engines. All these engines have to be adjusted to the grade ofoil to be used in order to get the best results. 

Kerosene engines are of two general types: the external-vaporizer type, in which the fuel is vaporized and mixed with air before or as it istaken into the cylinder; and the internal-vaporizer type, in which theliquid fuel is forced into the cylinder and vaporized by contact withthe hot gases or heated walls of a combustion chamber at the head of thecylinder. A number of special devices for vaporizing kerosene and thelighter distillates have been tried and used with some success. Heat isnecessary to vaporize the kerosene as quickly as it is required, and thedegree of heat must be held between the temperature of vaporization andthat at which the oil will be carbonized. The vapor must also bethoroughly and uniformly mixed with air in order to obtain completecombustion. As yet, no reliable data on these limiting temperatures forkerosene and similar oils have been obtained. No investigation has everbeen made of possible methods for preventing the oils from carbonizingat the higher temperatures, and the properties of explosive mixtures ofoil vapors and air have not been studied. This field of engineeringlaboratory research is of vital importance to the solution of thekerosene-engine problem. 

Distillates or fuel oils and the crude oils are much the cheapest of theliquid fuels, and if used efficiently in internal-combustion engineswould be by far the cheapest fuels available in many large districts. 

Several engine builders are developing kerosene vaporizers, which arebuilt as a part of the engine, or are adapted to each different engine, as required to obtain the best results. Most of these vaporizers use theheat and the exhaust gases to vaporize the fuel, but they differ greatlyin construction; some are of the retort type, and others are of thefloat-feed carburetter type. To what extent the lower-grade fuel oilscan be used with these vaporizers is yet to be determined. 

There are only a few successful oil engines on the American market. Themost prominent of these represent specific applications of the principalmethods of internal vaporization, and all except one are of the hot-bulbignition type. It will probably be found that no one of the 4-strokecycle, or 2-stroke cycle, engines is best for all grades of oil, butrather that each is best for some one grade. The Diesel engine is in aclass by itself, its cycle and method of control being somewhatdifferent from the others. 

An investigation of the comparative adaptability of gasoline and alcoholto use in internal-combustion engines, consisting of more than 2, 000tests, was made at the temporary fuel-testing plant of the GeologicalSurvey, at Norfolk, Va. , in 1907. A detailed report of these tests is inpreparation. [24] A similar investigation of the comparative adaptabilityof kerosenes has been commenced, with a view to obtaining data on theireconomical use, leading up to the investigation of the comparative fuelvalues of the cheaper distillates and crude petroleum, as beforediscussed. 

_Washing and Coking Tests. _--The investigations relating to thepreparation of low-grade coals, such as those high in ash or sulphur, byprocesses that will give them a higher market value or increase theirefficiency in use, are in charge of Mr. A. W. Belden. They include thewashing and coking tests of coals, and the briquetting of slack andlow-grade coal and culm-bank refuse so as to adapt these fuels forcombustion in furnaces, etc. 

This work has been conducted in the washery and coking plant temporarilylocated at Denver, Colo. , and in Building No. 32 at the Pittsburgtesting station, where briquetting is in progress. The details of thesetests are set forth in the various bulletins issued by the GeologicalSurvey. [25]

The washing tests are carried out in the following manner: As the rawcoal is received at the plant, it is shoveled from the railroad cars tothe hopper scale, and weighed. It then passes through the tooth-rollcrusher, where the lumps are broken down to a maximum size of 2½ in. Anapron conveyor delivers the coal to an elevator which raises it to oneof the storage bins. As the coal is being elevated, an average samplerepresenting the whole shipment is taken. An analysis is made of thissample of raw coal and float-and-sink tests are run to determine thesize to which it is necessary to crush before washing, and thepercentage of refuse with the best separation. From the data thusobtained, the washing machines are adjusted so that the washing test ismade with full knowledge of the separations possible under varyingpercentages of refuse. The raw coal is drawn from the bin and deliveredto a corrugated-roll disintegrator, where it is crushed to the sizefound most suitable, and is then delivered by the raw-coal elevator toanother storage bin. The arrangement of the plant is such that the coalmay be first washed on a Stewart jig, and the refuse then delivered toand re-washed on a special jig, or the refuse may be re-crushed and thenre-washed. 

When the coal is to be washed, it drops to the sluice box, where it ismixed with the water and sluiced to the jigs. In drawing off the washedcoal, or when the uncrushed raw coal is to be drawn from a bin andcrushed for the washing tests, however, a gate just below the coal-flowregulating gate is thrown in, and the coal falls into a central hopperinstead of into the sluice box. Ordinarily, this gate forms one side ofthe vertical chute. The coal in this central hopper is carried by achute to the apron conveyor, and thence to the roll disintegrator, or, in case it is washed coal, to a swing-hammer crusher. It will be notedthat coal, in this manner, can be drawn from a bin at the same time thatcoal is being taken from another bin, and sluiced to the jigs forwashing, the two operations not interfering in the least. 

The washed coal, after being crushed and elevated to the top of thebuilding, is conveyed by a chute to the coke-oven larry, and is weighedon the track scale, after which it is charged to the oven. The refuse issampled and weighed as it is wheeled to the dump pile, and from thissample the analysis is made and a float-and-sink test run to determinethe “loss of good coal” in the refuse and to show the efficiency of thewashing test. 

The coking tests have been conducted in a battery of two beehive ovens, one 7 ft. High and 12 ft. In diameter, the other, 6¼ ft. High and12 ft. In diameter. A standard larry with a capacity of 8 tons, andthe necessary scales for weighing accurately the coal charged and cokeproduced, complete the equipment. The coal is usually run through a rollcrusher which breaks it to about ½-in. Size, or through a Pennsylvaniahammer crusher. The fineness of the coals put through the hammer crushervaries somewhat, but the average, taken from a large number of samples, is as follows: Through ⅛-in. Mesh, 100%; over 10-mesh, 31. 43%; over20-mesh, 24. 29%; over 40-mesh, 22. 86%; over 60-mesh, 10 per cent. Theresults of the coking tests are set forth in detail in the variouspublications issued on this subject. [26]

Tests of coke produced in the illuminating-gas investigations beforereferred to, and a study of commercial coking and by-product plants, areincluded in these investigations. 

_Briquetting Investigations. _--These investigations are in charge of Mr. C. L. Wright, and are conducted in Building No. 32, which is offire-proof construction, having a steel-skeleton frame work, reinforced-concrete floors, and 2-in. Cement curtain walls, plastered onexpanded-metal laths. In this building two briquetting machines areinstalled, one an English machine of the Johnson type, and the other aGerman lignite machine of very powerful construction. 

The investigations include the possibility of making satisfactorycommercial fuels from lignite or low-grade coals which do not standshipment well, the benefiting of culm or slack coals which are wasted orsold at unremunerative prices, and the possibility of improving theefficiency of good coals. Some of the various forms of commercialbriquettes, American and foreign, are shown in Fig. 2, Plate XX. Afterundergoing chemical analysis, the coal is elevated and fed to a storagebin, whence it is drawn through a chute to a hopper on the weighingscales. There it is mixed with varying percentages of different kinds ofbinding material, and the tests are conducted so as to ascertain themost suitable binder for each kind of fuel, which will produce the mostdurable and weather-proof briquette at least cost, and the minimumquantity necessary to produce a good, firm briquette. After weighing, the materials to be tested are run through the necessary grinding andpulverizing machines and are fed into the briquetting machines, whencethe manufactured briquettes are delivered for loading or storage. Thematerials to be used in the German machine are also dried and cooledagain. 

 [Illustration: PLATE XXI. 

 Fig. 1. --Hand Briquetting Press. 

 Fig. 2. --Coal Briquetting Machine. ]

The briquettes made at this plant are then subjected to physical testsin order to determine their weathering qualities and their resistance toabrasion; extraction tests and chemical analyses are also made. Meanwhile other briquettes from the same lots are subjected tocombustion tests for comparison with the same coal not briquetted. Thesetests are made in stationary boilers, in house-heating boilers, onlocomotives, naval vessels, etc. , and the results, both of the processesof manufacture, and of the tests, are published in various bulletinsissued by the Geological Survey. [27]

The equipment includes storage bins for the raw coal, scales forweighing, machines for crushing or cracking the pitch, grinders, crushers, and disintegrators for reducing the coal to the desiredfineness, heating and mixing apparatus, presses and moulds for formingthe briquettes, a Schulz drier, and a cooling apparatus. 

There is a small experimental hand-briquetting press (Fig. 1, Plate XXI)for making preliminary tests of the briquetting qualities of the variouscoals and lignites. With this it is easily possible to vary thepressure, heat, percentage and kind of binder, so as to determine thebest briquetting conditions for each fuel before subjecting it tolarge-scale commercial tests in the big briquetting machines. 

This hand press will exert pressures up to 50 tons or 100, 000 lb. Persq. In. , on a plunger 3 in. In diameter. This plunger enters a mould, which can be heated by a steam jacket supplied with ordinary saturatedsteam at a pressure of 125 lb. , and compresses the fuel into abriquette, 8 in. Long, under the conditions of temperature and pressuredesired. 

The Johnson briquetting machine, which requires 25 h. P. For itsoperation, exerts a pressure of about 2, 500 lb. Per sq. In. , and makesbriquettes of rectangular form, 6¾ by 4¼ by 2½ in. , and having anaverage weight of about 3¾ lb. The capacity of the machine (Fig. 2, Plate XXI) is about 3. 8 tons of briquettes per 8-hour day. 

Under the hopper on the scales for the raw material is a square woodenreciprocal plunger which pushes the fuel into a hole in the floor at auniform rate. The pitch is added as uniformly as possible by hand, asthe coal passes this hole. Under this hole a horizontal screw conveyorcarries the fuel and pitch to the disintegrator, in front of which, inthe feeding chute, there is a powerful magnet for picking out any piecesof iron which might enter the machine and cause trouble. 

The ground mixture is elevated from the disintegrator to a point abovethe top of the upper mixer of the machine. At the base of this cylinder, steam can be admitted by several openings to heat the material to anydesired temperature, usually from 180° to 205° Fahr. There, a plunger, making 17 strokes per min. , compresses two briquettes at each stroke. 

The German lignite-briquetting machine (Figs. 18 and 19) was made by theMaschinenfabrik Buckau Actien-Gesellschaft, Magdeburg, Germany. Lignitefrom the storage room on the third floor of the building is fed into oneend of a Schulz tubular drier (Fig. 1, Plate XXII), which is similar toa multi-tubular boiler set at a slight angle from the horizontal, andslowly revolved by worm and wheel gearing, the lignite passing throughthe tubes and the steam being within the boiler. From this drier thelignite passes through a sorting sieve and crushing rolls to a coolingapparatus, which consists of four horizontal circular plates, about 13ft. In diameter, over which the dried material is moved by rakes. Aftercooling, the material is carried by a long, worm conveyor to a largehopper over the briquette press, and by a feeding box to the press (Fig. 2, Plate XXII). 

The press, which is of the open-mould type, consists of a ram and dieplates, the latter being set so as to make a tube which gradually taperstoward the delivery end of the machine. The briquettes have across-section similar to an ellipse with the ends slightly cut off; theyare about 1¼ in. Thick and average about 1 lb. In weight (Fig. 2, PlateXX). The press is operated by a direct connection with a steam engine of150 h. P. , the base of which is continuous with that of the press. Theexhaust steam from the engine is used to heat the driver. 

The plunger makes from 80 to 100 strokes per min. , the pressure exertedranging from 14, 000 to 28, 000 lb. Per sq. In. , the capacity of themachine being 1 briquette per stroke, or from 2½ to 3 tons of completedbriquettes per hour. It is expected that no binder will be needed forpractically all the brown lignite briquetted by this machine, thusreducing the cost as compared with the briquetting of coals, whichrequire from 5 to 7% of water-gas, pitch binder costing more than 50cents per ton of manufactured briquettes. 

 [Illustration: Fig. 18. 

 LONGITUDINAL-SECTION OF LIGNITE-BRIQUETTING PLANT]

 [Illustration: Fig. 19. 

 CROSS-SECTION OF LIGNITE-BRIQUETTING PLANT]

_Peat Investigations. _--Investigations into the distribution, production, origin, nature, and uses of peat are being conducted by Mr. C. A. Davis, and include co-operative arrangements with State GeologicalSurveys and the Geologic Branch of the U. S. Geological Survey. Theseorganizations conduct surveys which include the mapping of the peatdeposits in the field, the determination of their extent andlimitations, the sampling of peat from various depths, and thetransmittal of samples to the Pittsburg laboratories for analysis andtest. [28]

This work is co-ordinated in such a manner as to result in uniformmethods of procedure in studying the peat deposits of the United States. The samples of peat are subjected to microscopic examination, in orderto determine their origin and age, and to chemical and physical tests atthe laboratories in Pittsburg, so as to ascertain the chemicalcomposition and calorific value, the resistance to compressive strains, the ash and moisture content, drying properties, resistance to abrasion, etc. Occasionally, large quantities of peat are disintegrated andmachined, and portions, after drying for different periods, aresubjected to combustion tests in steam boilers and to tests in the gasproducer, to ascertain their efficiency as power producers. 

_Results. _--The full value of such investigations as have been describedin the preceding pages cannot be realized for many years; but, evenwithin the four years during which this work has been under way, certaininvestigations have led to important results, some of which may bebriefly mentioned:

The chemical and calorific determinations of coals purchased for the useof the Government have resulted in the delivery of a better grade offuel without corresponding increase in cost, and, consequently, insaving to the Government. Under this system, of purchasing its coalunder specifications and testing, the Government is getting more nearlywhat it pays for and is paying for what it gets. These investigations, by suggesting changes in equipment and methods, are also indicating thepracticability of the purchase of cheaper fuels, such as bituminous coaland the smaller sizes of pea, buckwheat, etc. , instead of the moreexpensive sizes of anthracite, with a corresponding saving in cost. TheGovernment’s fuel bill now aggregates about $10, 000, 000 yearly. 

 [Illustration: PLATE XXII. 

 Fig. 1. --Dryer for Lignite Briquetting Press. 

 Fig. 2. --Lignite Briquetting Machine. ]

The making and assembling of chemical analyses and calorificdeterminations (checked by other tests) of carefully selected samples ofcoals from nearly 1, 000 different localities, in the different coalfields of the United States, with the additions, from time to time, ofsamples representing parts of coal fields or newly opened beds of coalin the same field, furnish invaluable sources of accurate information, not only for use of the Government, but also for the general public. Ofthe above-mentioned localities, 501 were in the public-land States and427 in the Central, Eastern, and Southern States. 

The chemical analyses of the coals found throughout the United Stateshave been made with such uniformity of method, both as to collectionof samples and analytical procedure, as to yield results strictlycomparable for coals from all parts of the country, and furnish completeinformation, as a basis for future purchases and use by the Governmentand by the general public, of all types of American coals. 

Other researches have resulted in the acquirement of valuableinformation regarding the distribution of temperature in the fuel bed ofgas producers and furnaces, showing a range of from 400° to 1, 300°cent. , and have thus furnished data indicating specific difficulties tobe overcome in gas-producer improvements for greater fuel efficiency. 

The recent studies of the volatile matter in coal, and its relation tothe operation of coke ovens and other forms of combustion, havedemonstrated that as much as one-third of this matter is inert andnon-combustible, a fact which may have a direct bearing on smokeprevention by explaining its cause and indicating means for itsabatement. 

Experiments in the storage of coal have proven that oxygen is absorbedduring exposure to air, thereby causing, in some cases, a deteriorationin heating value, and indicating that, for certain coals, in case theyare to be stored a long time for naval and other purposes, storage underwater is advisable. 

The tests of different coals under steam boilers have shown thepossibility of increasing the general efficiency of hand-fired steamboilers from 10 to 15% over ordinary results. If this saving could bemade in the great number of hand-fired boilers now being operated in allparts of the United States, it would result in large saving in the fuelbill of the country. Experiments which have been made withresidence-heating boilers justify the belief that it will be possible toperfect such types of boilers as may economically give a smokelessoperation. The tests under steam boilers furnish specific information asto the most efficient method of utilizing each of a number of differenttypes of coal in Government buildings and power plants in differentparts of the country. 

The tests in the gas producer have shown that many fuels of such lowgrade as to be practically valueless for steam-furnace purposes, including slack coal, bone coal, and lignite, may be economicallyconverted into producer gas, and may thus generate sufficient power torender them of high commercial value. 

Practically every shipment out of several hundred tested in the gasproducers, including coals as high in ash content as 45%, and lignitesand peats high in moisture, has been successfully converted intoproducer gas which has been used in operating gas engines. It has beenestimated that on an average there was developed from each coal testedin the gas-producer plant two and one-half times the power developedwhen used in the ordinary steam-boiler plant, and that such relativeefficiencies will probably hold good for the average plant of moderatepower capacity, though this ratio may be greatly reduced in large steamplants of the most modern type. It was found that the low-grade lignitesof North Dakota developed as much power, when converted into producergas, as did the best West Virginia bituminous coals when utilized underthe steam boiler; and, in this way, lignite beds underlying from20, 000, 000 to 30, 000, 000 acres of public lands, supposed to have littleor no commercial value, are shown to have a large value for powerdevelopment. 

The tests made with reference to the manufacture and combustion ofbriquetted coal have demonstrated conclusively that by this means manylow-grade bituminous coals and lignites may have their commercial valueincreased to an extent which more than covers the increased cost ofmaking; and these tests have also shown that bituminous coals of thehigher grades may be burned in locomotives with greatly increasedefficiency and capacity and with less smoke than the same coal notbriquetted. These tests have shown that, with the same fuel consumptionof briquettes as of raw coal, the same locomotive can very materiallyincrease its hauling capacity and thus reduce the cost oftransportation. 

The investigations into smoke abatement have indicated clearly that eachtype of coal may be burned practically without smoke in some type offurnace or with some arrangement of mechanical stoker, draft, etc. Theelimination of smoke means more complete combustion of the fuel, andconsequently less waste and higher efficiency. 

The investigations into the waste of coal in mining have shown theenormous extent of this waste, aggregating probably from 300, 000, 000 to400, 000, 000 tons yearly, of which at least one-half might be saved. Itis being demonstrated that the low-grade coals, high in sulphur and ash, now left underground, can be used economically in the gas producer forpower and light, and, therefore, should be mined at the same time thatthe high-grade coal is being removed. Moreover, attention is now beingcalled to the practicability of a further large reduction of wastethrough more efficient mining methods. 

The washing tests have demonstrated the fact that many coals, too highin ash and sulphur for economic use under the steam boiler or forcoking, may be rendered of commercial value by proper treatment in thewashery. The coking tests have also demonstrated that, by proper methodsof preparation for and manipulation in the beehive oven, many coalswhich were not supposed to be of economic value for coking purposes, maybe rendered so by prior washing and proper treatment. Of more than 100coals tested during 1906 from the Mississippi Valley and the EasternStates, most of which coals were regarded as non-coking, all except 6were found, by careful manipulation, to make fairly good coke forfoundry and other metallurgical purposes. Of 52 coals from the RockyMountain region, all but 3 produced good coke under proper treatment, though a number of these had been considered non-coking coals. 

Investigations into the relative efficiency of gasoline and denaturedalcohol as power producers, undertaken in connection with work for theNavy Department, have demonstrated that with proper manipulation of thecarburetters, igniters, degree of compression, etc. , denatured alcoholhas the same power-producing value, gallon for gallon, as gasoline. Thisis a most interesting development, in view of the fact that the heatvalue of a gallon of alcohol is only a little more than 0. 6 that of agallon of gasoline. To secure these results, compressions of from 150 to180 lb. Per sq. In. Were used, these pressures involving an increase inweight of engine. Although the engine especially designed for alcoholwill be heavier than a gasoline engine of the same size, it will have asufficiently greater power capacity so that the weight per horse-powerneed not be greater. 

Several hundred tons of peat have been tested to determine methods ofdrying, compressing into briquettes, and utilization for powerproduction in the gas producer. In connection with these peatinvestigations, a reconnoissance survey has been made of the peatdeposits of the Atlantic Coast. Samples have been obtained by boring todifferent depths in many widely distributed peat-bogs, and these sampleshave been analyzed and tested in order to determine their origin, nature, and fuel value. 

The extent and number of tests from which these results have beenderived will be appreciated from the fact that, in three years, nearly15, 000 tests were made, in each of which large quantities of fuel wereconsumed. These tests involved nearly 1, 250, 000 physical observationsand 67, 080 chemical determinations, made with a view to analyze theresults of the tests and to indicate any necessary changes in themethods as they progressed. For coking, cupola, and washing, 596 tests, of which nearly 300 involved the use of nearly 1, 000 tons of coal, havebeen made at Denver. For briquetting, 312 tests have been made. Briquettes have been used in combustion tests in which 250 tons ofbriquetted coal were consumed in battleship tests, 210 tons intorpedo-boat tests, 320 tons in locomotive tests on three railwaysystems, and 70 tons were consumed under stationary steam boilers. Ofproducer gas tests, 175 have been made, of which 7 were long-time runsof a week or more in duration, consuming in all 105 tons of coal. Therehave been 300 house-heating boiler tests and 575 steam-boiler tests;also, 83 railway-locomotive and 23 naval-vessel tests have been made onrun-of-mine coal in comparison with briquetted coal; also, 125 testshave been made in connection with heat-transmission experiments, and2, 254 gasoline- and alcohol-engine tests. Nearly 10, 000 samples of coalwere taken for analysis, of which 3, 000 were from public-land States. Nearly 5, 000 inspection samples, of coal purchased by the Government forits use, have been taken and tested. 

The results of the tests made in the course of these investigations, assummarized, have been published in twelve separate Bulletins, three ofwhich, Nos. 261, 290, and 332, set forth in detail the operations of thefuel-testing plant for 1904, 1905, and 1906. Professional Paper No. 48, in three volumes, describes in greater detail each stage of theoperations for 1904 and 1905. 

Separate Bulletins, descriptive of the methods and results of the workin detail, have been published, as follows: No. 323, Experimental workconducted in the chemical laboratory; No. 325, A study of four hundredsteaming tests; No. 334, Burning of coal without smoke in boiler plants;No. 336, Washing and coking tests of coal, and cupola tests of coke; No. 339, Purchase of coal under specifications on basis of heating value;No. 343, Binders for coal briquettes; No. 362, Mine sampling andchemical analyses of coals in 1907; No. 363, Comparative tests ofrun-of-mine and briquetted coal on locomotives, including torpedo-boattests, and some foreign specifications for briquetted fuel; No. 366, Tests of coal and briquettes as fuel for house-heating boilers; No. 367, Significance of drafts in steam-boiler practice; No. 368, Coking andwashing tests of coal at Denver; No. 373, Smokeless combustion of coalin boiler plants, with a chapter on central heating plants; No. 378, Results of purchasing coal under Government specifications; No. 382, The effect of oxygen in coal; and, No. 385, Briquetting tests atNorfolk, Va. 

DISCUSSION

KENNETH ALLEN, M. Am. Soc. C. E. --The speaker would like to know whetheranything has been done in the United States toward utilizing marsh mudfor fuel. 

In an address by Mr. Edward Atkinson, before the New England Water WorksAssociation, in 1904, on the subject of “Bog Fuel, ” he referred to itsextensive use in Sweden and elsewhere, and intimated that there was awide field for its use in America. 

The percentage of combustible material in the mud of ordinary marshlands is very considerable, and there are enormous deposits readilyavailable; but it is hardly probable that its calorific value issufficiently high to render its general use at this time profitable. 

As an example of the amount of organic matter which may remain stored inthese muds for many years, the speaker would mention a sample taken fromthe bottom of a trench, which he had analyzed a few years ago. Althoughtaken from a depth of about 15 ft. , much of the vegetable fiber remainedintact. The material proved to be 70¾% volatile. 

Possibly before the existing available coal deposits are exhausted, theexploitation of meadow muds for fuel may become profitable. 

HENRY KREISINGER, Esq. [29] (by letter). --Mr. Wilson gives a briefdescription of a long furnace and an outline of the research work whichis being done in it. It may be well to discuss somewhat more fully theproposed investigations and point out the practical value of thefindings to which they may lead. 

In general, the object is to study the process of combustion of coal. When soft coal is burned in any furnace, part of the combustible isdriven off shortly after charging, and has to be burned in the spacebetween the fuel bed and the exit of the gases, which is called thecombustion space. There is enough evidence to show that, with a constantair supply, the completeness of the combustion of the volatilecombustible depends on the length of time the latter stays within thecombustion space; but, with a constant rate of charging the coal, thislength of time depends directly on the extent of the combustion space. Thus, if the volume of the volatile combustible evolved per second andthe admixed air is 40 cu. Ft. , and the extent of the combustion space is80 cu. Ft. , the average time the gas will stay within the latter is 2sec. ; if the combustion space is 20 cu. Ft. , the average time themixture can stay in this space is only ½ sec. , and its combustion willbe less complete than in the first case. Thus it is seen that the extentof the combustion space of a furnace is an important factor in theeconomic combustion of volatile coals. The specific object of theinvestigations, thus far planned, is to determine the extent of thecombustion space required to attain practically complete combustion whena given quantity of a given coal is burned under definite conditions. With this object in view, the furnace has been provided with acombustion space large enough for the highest volatile coals and for thehighest customary rate of combustion. To illustrate the application ofthe data which will be obtained by these experiments, the followingqueries are given:

Suppose it is required to design a furnace which will burn coal from acertain Illinois mine at the rate of 1, 000 lb. Per hour, with aresulting temperature of not less than 2, 800° Fahr. How large acombustion space is required to burn, with practical completeness, thevolatile combustible? What completeness of combustion can be attained, if the combustion space is only three-fourths of the required extent? Inthe present state of the knowledge of the process of combustion of coal, these queries cannot be answered definitely. In the literature oncombustion one may find statements that the gases must be completelyburned before leaving the furnace or before they strike the coolingsurfaces of the boiler; but there is no definite information availableas to how long the gases must be kept in the furnace or how large thecombustion space must be in order to obtain practically completecombustion. It is strange that so little is known of such an old art asthe combustion of coal. 

The research work under consideration is fundamentally a problem inphysical chemistry, and, for that reason, has been assigned to acommittee consisting of the writer as Engineer, Dr. J. C. W. Frazer, Chemist, and Dr. J. K. Clement, Physicist. The outcome of theinvestigation may prove of extreme interest to mechanical and fuelengineers, and to all who have anything to do with the burning of coalor the construction of furnaces. In the experiments thus far planned thefollowing factors will be considered:

_Effect of the Nature of Coal on the Extent of Combustion SpaceRequired. _--The steaming coals mined in different localities evolvedifferent volumes of volatile combustible, even when burned at the samerate. The coal which analyzes 45% of volatile matter evolves a muchgreater volume of gases and tar vapors than that analyzing only 15 percent. These evolved gases and tar vapors must be burned in the space. Consequently, a furnace burning high volatile coal must have a muchlarger combustion space than that burning coal low in volatilecombustible. 

There is enough evidence to show that the extent of combustion spacerequired to burn the volatile combustible depends, not only on thevolume of the combustible mixture, but also on the chemical compositionof the volatile combustible. Thus the volatile combustible of lowvolatile coal, when mixed with an equal volume of air, may require 1sec. In the combustion space to burn practically to completeness, whileit may require 2 sec. To burn the same volume of the volatilecombustible of high volatile coal with the same completeness; so thatthe extent of the combustion space required to burn various kinds ofcoal may not be directly proportional to the volatile matter of thecoal. 

_Effect of the Rate of Combustion on the Extent of Combustion SpaceRequired. _--With the same coal, the volume of the volatile combustibledistilled from the fuel bed per unit of time varies as the rate ofcombustion. Thus, when this rate is double that of the standard, thevolume of gases and tar vapors driven from the fuel is about doubled. Tothis increased volume of volatile combustible, about double the volumeof air must be added, and, if the mixture is to be kept the same lengthof time within the combustion space, the latter should be about twice aslarge as for the standard rate of combustion. Thus the combustion spacerequired for complete combustion varies, not only with the nature of thecoal, but also with the rate of firing the fuel, which, of course, isself-evident. 

_Effect of Air Supply on the Extent of Combustion SpaceRequired. _--Another factor which influences the extent of the combustionspace is the quantity of air mixed with the volatile combustible. Perhaps, within certain limits, the combustion space may be decreasedwhen the supply of air is increased. However, any statement at presentis only speculation; the facts must be determined experimentally. Onefact is known, namely, that, in order to obtain higher temperatures ofthe products of combustion, the air supply must be decreased. 

_Effect of Rate of Heating of Coal on the Extent of Combustion SpaceRequired. _--There is still another factor, a very important one, which, with a given coal and any given air supply, will influence the extent ofthe combustion space. This factor is the rate of heating of the coalwhen feeding it into the furnace. The so-called “proximate” analysis ofcoal is indeed only very approximate. When the analysis shows, say, 40%of volatile matter and 45% of fixed carbon, it does not mean that thecoal is actually composed of so much volatile matter and so much fixedcarbon; it simply means that, under a certain rate of heating attainedby certain standard laboratory conditions, 40% of the coal has beendriven off as “volatile matter. ” If the rate or method of heating weredifferent, the amount of volatile matter driven off would also bedifferent. Chemists state that it is difficult to obtain accurate checkson “proximate” analysis. To illustrate this factor, further referencemay be made to the operation of the up-draft bituminous gas producers. In the generator of such producers the tar vapors leave the freshlyfired fuel, pass through the wet scrubber, and are finally separated bythe tar extractor as a black, pasty substance in a semi-liquid state. Ifthis tar is subjected to the standard proximate analysis, it will beshown that from 40 to 50% of it is fixed carbon, although it left thegas generator as volatile matter. It is desired to emphasize the factthat different rates of heating of high volatile coals will not onlydrive off different percentages of volatile matter, but that the latteritself varies greatly in chemical composition and physical properties asregards inflammability and rapidity of combustion. Thus it may be saidthat the extent of the combustion space required for the completeoxidation of the volatile combustible depends on the method of chargingthe fuel, that is, on how rapidly the fresh fuel is heated. If thisfactor is given proper consideration, it may be possible to reduce verymaterially the necessary space required for complete combustion. 

_The Effect of the Rate of Mixing the Volatile Combustible and Air onthe Extent of the Combustion Space. _--When studying the effectsdiscussed in the preceding paragraphs, the rate of mixing the volatilecombustible with the supply of air must be as constant as practicable. At first, tests will be made with no special mixing devices, the mixingwill be accomplished entirely by the streams of air entering the furnaceat the stoker, and by natural diffusion. Although there appears to beviolent stirring of the gases above the fuel bed, the mixture of thegases does not become homogeneous until they are about 10 or 15 ft. Fromthe stoker. The mixing caused by the air currents forced into thefurnace at the stoker is very distinct, and can be readily observedthrough the peep-hole in the side wall of the Heine boiler, opposite thelong combustion chamber. This mixing is shown in Fig. 20. _A_ is acurrent of air forced from the ash-pit directly upward through the fuelbed; _B_ and _B_ are streams of air forced above the fuel bed throughnumerous small openings at the furnace side of each hopper. Thosecurrents cause the gases to flow out of the furnace in two spirals, asshown in Fig. 20. The velocity of rotation on the outside of the twospirals appears to be about 10 ft. Per sec. , when the rate of combustionis about 750 lb. Of coal per hour. It is reasonable to expect that whenthe rate of mixing is increased by building piers and other mixingstructures immediately back of the grate, the completeness of thecombustion will be effected in less time, and a smaller combustion spacewill be required. Thus, the mixing structures may be an important factorin the extent of the required combustion space. 

To sum up, it can be said that the extent of the space required toobtain a combustion which can be considered complete for all practicalpurposes, depends on the following factors:

 (_a_). --Nature of coal, (_b_). --Rate of combustion, (_c_). --Supply of air, (_d_). --Rate of heating fuel, (_e_). --Rate of mixing volatile combustible and air. 

Just how much the extent of the combustion space required will beinfluenced by these factors is the object of the experiments underdiscussion. 

_The Scope of the Experiments. _--With this object in view, as explainedin the preceding paragraphs, the following series of experiments areplanned:

 [Illustration: Fig. 20. 

 SECTION THROUGH STOKER SHOWING MIXING OF GASES CAUSED BY CURRENTS OF AIR]

Six or eight typical coals are to be selected, each representing acertain group of nearly the same chemical composition. Each series willconsist of several sets of tests, each set being run with all theconditions constant except the one, the effect of which on the size ofthe combustion space is to be investigated. Thus a set of four or fivetests will be made, varying in rate of combustion from 20 to 80 lb. Ofcoal per square foot of grate per hour, keeping the supply of air perpound of combustible and the rate of heating constant. This set willshow the effect of the rate of combustion of the coal on the extent ofspace required to obtain combustion which is practically complete. Othervariables, such as composition of coal, supply of air, and rate ofheating, remain constant. 

Another set of four or five tests will be made with the same coal and atthe same rate of combustion, but the air supply will be different foreach test. This set of tests will be repeated for two or three differentrates of combustion. Thus each of these sets will give the effect of theair supply on the extent of combustion space when the coal and rate ofcombustion remain constant. 

Still another set of tests should be made in which the time of heatingthe coal when feeding it into the furnace will vary from 3 to 30 min. Ineach of the tests of this set, the rate of combustion and the air supplywill be kept constant, and the set will be repeated for two or threerates of combustion and two or three supplies of air. Each of these setsof tests will give the effect of the rate of heating of fresh fuel onthe extent of combustion space required to burn the distilled volatilecombustible. These sets of experiments will require a modification inthe stoker mechanism, and, on that account, may be put off until all theother tests on the other selected typical coals are completed. As theinvestigation proceeds, enough may be learned so that the number oftests in each series may be gradually reduced. After all the desirabletests are made with the furnace as it stands, several kinds of mixingstructures will be built successively back of the stoker and tried, onekind at a time, with a set of representative tests. Thus theeffectiveness of such mixing structures will be determined. 

_Determining the Completeness of Combustion. _--The completeness ofcombustion in the successive cross-sections of the stream of gases isdetermined mainly by the chemical analysis of samples of gases collectedthrough the openings at these respective cross-sections. The first ofthese cross-sections at which gas samples are collected, passes throughthe middle of the bridge wall; the others are placed at intervals of 5ft. Through the entire length of the furnace. Measurements of thetemperature of the gases, and direct observations of the length andcolor of the flames and of any visible smoke will be also made throughthe side peep-holes. These direct observations, together with the gasanalysis, will furnish enough data to determine the length of travel ofthe combustible mixture to reach practically complete combustion. 

In other words, these observations will determine the extent of thecombustion space for various kinds of coal when burned under certaingiven conditions. Direct observations and the analysis of gases atsections nearer the stoker than that at which the combustion ispractically complete, will show how the process of combustion approachesits completion. This information will be of extreme value in determiningthe effect of shortening the combustion space on the loss of heat due toincomplete combustion. 

_Method of Collecting Gas Samples. _--The collection of gas samples is adifficult problem in itself, when one considers that the temperature ofthe gases, as they are in the furnace, ranges from 2, 400° to 3, 200°Fahr. ; consequently, the samples must be collected with water-cooledtubes. Thus far, about 25 preliminary tests have been made. These testsshow that the composition of the gases at the cross-sections near thestoker is not uniform, and that more than one sample must be taken fromeach cross-section. It was decided to take 9 samples from thecross-section immediately back of the stoker, and reduce the number inthe sections following, according to the uniformity of the gascomposition. Thus, about 35 simultaneous gas samples must be taken foreach test. The samples will be subjected, not only to the usualdetermination of CO_{2}, O_{2} and CO, but to a complete analysis. It isalso realized that some of the carbon-hydrogen compounds which, at thefurnace temperature, exist as heavy gases, are condensed to liquids andsolids when cooled in the sampling tubes, where they settle and tend toclog it. To neglect the presence of this form of the combustible wouldintroduce considerable error in the determination of the completeness ofcombustion at any of the cross-sections. Therefore, special water-cooledsampling tubes are constructed and equipped with filters which separatethe liquid and solid combustible from the gases. The contents of thesefilters are then also subjected to complete analysis. To obtainquantitative data, a measured quantity of gases must be drawn throughthese filtering sampling tubes. 

_The Measuring of Temperatures. _--At present the only possible knownmethod of measuring the temperature of the furnace gases is by opticaland radiation pyrometers. Platinum thermo-couples are soon destroyed bythe corrosive action of the hot gases. The pyrometers used at presentare the Wanner optical pyrometer and the Fery radiation pyrometer. 

_The Flow of Heat Through Furnace Walls. _--An interesting sideinvestigation has developed, in the study of the loss of heat throughthe furnace walls. In the description of this experimental furnace ithas been said that the side walls contained a 2-in. Air space, which, inthe roof, was replaced with a 1-in. Layer of asbestos. To determine therelative resistance to heat flow of the air space and the asbestoslayer, 20 thermo-couples were embedded, in groups of four, to differentdepths at three places in the side wall and at two places in the roof. In the side wall, one of the thermo-couples of each group was placed inthe inner wall near the furnace surface; the second thermo-couple wasplaced in the same wall, but near the surface facing the air space; thethird thermo-couple was placed in the outer wall near the inner surface;and the fourth was placed near the outer surface in the outer wall. Inthe roof the second and third thermo-couples were placed in the bricknear the surface on each side of the asbestos layer. Thesethermo-couples have shown that the temperature drop across the 2-in. Airspace was much less than that across the 1-in. Layer of asbestos; infact, that it was considerably less than the temperature drop throughthe same thickness of the brick wall. 

The results obtained prove that, as far as heat insulation is concerned, air spaces in furnace walls are undesirable. The heat is not conductedthrough the air, but leaps across the space by radiation. In furnaceconstruction a solid wall is a better heat insulator than one of thesame total thickness containing an air space. If it is necessary tobuild a furnace wall in two parts on account of unequal expansion, thespace between the two walls should be filled with some solid, cheap, non-conducting materials, such as ash, sand, or crushed brick. A moredetailed account of these experiments may be found in a Bulletin of theU. S. Geological Survey entitled “The Flow of Heat Through FurnaceWalls. ”

WALTER O. SNELLING, Esq. [30] (by letter). --The work of the United StatesTesting Station at Pittsburg has been set forth so fully by Mr. Wilsonthat a further statement as to the results achieved may seem likerepetition. It would be most unlikely, however, that studies of suchvariety should possess no other value than along the direct lines beinginvestigated. In the case of the Mine Accidents Division, at least, itis certain that the indirect benefits of some of the studies have beenfar-reaching, and are now proving of value in lines far removed fromthose which were the primary object of the investigation. They aredeveloping facts which will be of great value to all engineers orcontractors engaged in tunneling or quarrying. As the writer’sexperience has been solely in connection with the chemical examinationof explosives, he will confine his discussion to this phase. 

In studying the properties of various explosives, and in testing work toseparate those in which the danger of igniting explosive mixtures ofcoal dust and air, or of fire-damp and air, is greatest, from those inwhich this danger is least, much information has been collected. Mr. Wilson has described many of the tests, and it can be readily seen thatin carrying out these and other tests on each of the explosivessubmitted, a great many facts relating to the properties of explosivecompounds have been obtained, which were soon found to be of decidedvalue in directions other than the simple differentiation of explosiveswhich are safe from those which are unsafe in the presence of explosivemixtures of fire-damp or coal dust. 

The factors which determine the suitability of an explosive for work inmaterial of any particular physical characteristics depend on therelationship of such properties as percussive force (or the initial blowproduced by the products of the decomposition of the explosive at themoment of explosion), and the heaving force (or the continued pressureproduced by the products of the decomposition, after the initial blow atthe instant of detonation). Where an explosive has been used in coal orrock of a certain degree of brittleness, and where the work of theexplosive with that particular coal is not thoroughly satisfactory, itbecomes evident that through the systematic use of the informationavailable at the Testing Station (and now in course of publication inthe form of bulletins), in regard to the relationship between percussiveand heaving forces in different explosives, as shown by the tests withsmall lead blocks, the Trauzl test, and the ballistic pendulum, thatexplosives can be selected which, possessing in modified form theproperties of the explosive not entirely satisfactory in that type ofcoal or rock, would combine all the favorable properties of the firstexplosive, together with such additional advantages as would come fromits added adaptation to the material in which it is to be used. 

For example, if the explosive in use were found to have too great ashattering effect on the coal, an examination of the small lead-blocktest of this explosive, and a comparison of this with lead-block testsof other explosives having practically the same strength, as shown bythe ballistic pendulum, will enable the mine manager to select fromthose already on the Permissible List (and therefore vouched for inregard to safety in the presence of gas and coal dust, when used in aproper way), some explosive which will have the same strength, and yetwhich, because of lessened percussive force or shattering effect, willproduce coal in the manner desired. If one takes the other extreme, andconsiders a mine in which the product is used exclusively for thepreparation of coke (and therefore where shattering of the coal is in noway a disadvantage), the mine superintendent’s interest will beprimarily to select an explosive which, as indicated by suitablelead-block, Trauzl, and ballistic pendulum tests, will produce thegreatest amount of coal at the least cost. 

As the cost of the explosive does not form any part of the tablesprepared by the Testing Station, the relative cost must be computed fromthe manufacturer’s prices, but the results tabulated by the Station willcontain all the other data necessary to give the mine superintendent(who cares to take the small amount of trouble necessary to familiarizehimself with the tables) all the information which is required tocompare the action of one explosive with that of any other explosivetested. 

In this way it is seen that, aside from the primary consideration ofsafety in the presence of explosive mixtures of fire-damp and coal dust(a condition alike fulfilled by all explosives admitted to thePermissible List), the data prepared by the Testing Station also givethe information necessary to enable the discriminating mine manager toselect an explosive adapted to the particular physical qualities of thecoal at his mine, or to decide intelligently between two explosives ofthe same cost on the basis of their actual energy content in theparticular form of the heaving or percussive force required in his work. 

Up to the present time the investigations have been confined toexplosives used in coal mining, because the Act of Congress establishingthe Testing Station has thus limited its work. Accordingly, it is notpossible to compare, on the systematic basis just mentioned, theexplosives generally used in rock work. It is probable that, if the Billnow before Congress in regard to the establishment of a Bureau of Minesis passed, work of this character will be undertaken, and the tables ofexplosives now prepared will be extended to cover all those intended forgeneral mining and quarrying use. Data of such character areunobtainable to-day, and, as a result, a considerable percentage ofexplosives now used in all mining operations is wasted, because of theirlack of adaptation to the materials being blasted. It is well known, forexample, that when an explosive of high percussive force is used inexcavating in a soft or easily compressed medium, a considerablepercentage of its force is wasted as heat energy, performing no otherfunction than the distortion and compression of the material in which itis fired, without exerting either an appreciable cracking or fissuringeffect, or a heaving or throwing of the material. 

Owing to lack of information in regard to the exact relationship betweenthe percussive and the heaving force in particular explosives, thiswaste, as compared with the quantity required for the work with aproperly balanced material, will continue; but it is to be hoped that itwill soon be possible to give the mining and quarrying industriessuitable information in regard to the properties of the variousexplosives, so that the railroad contractor and the metal miner may havethe same simple and exact means of discrimination between suitable andunsuitable explosives that is now being provided for the benefit of thecoal miner. 

Another of the important but indirect benefits of this work has been theproduction of uniformity of strength and composition in explosives. Anexample of this helpful influence is the standardization of detonatingcaps and electric detonators. In the early days of the explosiveindustry, it was apparently advantageous for each manufacturer to have aseparate system of trade nomenclature by which to designate thestrengths of the different detonators manufactured by him. The necessityand even the advantage of such methods have long been outgrown, and yet, until the past year, the explosive industry has had to labor underconditions which made it almost impossible for the user of explosives tocompare, in cost or strength, detonators of different manufacturers; orto select intelligently the detonator best suited to the explosive to beused. After conference with the manufacturers of detonating caps andelectric detonators, a standard system of naming the strengths of theseproducts has been selected by the Testing Station, and has met with amost hearty response. It is encouraging to note that, in recent tradecatalogues, detonators are named in such a way as to enable the user todetermine directly the strength of the contained charge, which is adecided advantage to every user of explosives and also to manufacturers. 

The uniformity of composition of explosives (and many difficulties inmining work and many accidents have been rightly or wrongly attributedto lack of uniformity) may be considered as settled in regard to allthose on the Permissible List. One of the conditions required of everyexplosive on that list is that its composition must continuesubstantially the same as the samples submitted originally for officialtest. Up to the present, all explosives admitted to the Permissible Listhave maintained their original composition, as determined by subsequentanalyses of samples selected from mines in which the explosive was inuse, and comparison with the original samples. 

The data assembled by the Testing Station in regard to particularexplosives have also been of great benefit to the manufacturers. Whenthe explosives tests were commenced, comparatively few explosives werebeing made in the United States for which it was even claimed by themanufacturers that they were at all safe in the presence of explosivemixtures of gas or coal dust. It was evident that, without systematictests, very little knowledge of the safety or lack of safety of anyparticular explosive could ever be gained, and, consequently, the userof explosives was apt to regard with incredulity any claim by themanufacturer in regard to the qualities of safety. Owing to lack ofproof, this was most natural; and it was also evident that the very slowprocess of testing, which was offered by a study of mine explosionsduring past years, was sufficient only to prove the danger of blackpowder, and not in any way to indicate the safety of any of the brandsof mining powder for which this property was claimed. Indeed, one of thefew explosives to which the name, “safety, ” was attached, at the timethe Government experiments were first undertaken, was found to beanything but safe when tested in the gallery, although there is noreason to believe that the makers of this and other explosives claiming“safety” for their product, did not have the fullest confidence in theirsafety. 

The Testing Station offered the first opportunity in the United Statesto obtain facts in regard to the danger of any particular explosive inthe presence of explosive mixtures of gas or coal dust. With mostcommendable energy, the manufacturers of explosives, noting the earlyfailures of their powders in the testing gallery, began at once tomodify them in such ways as suggested by the behavior of the explosiveswhen under test, and, in a short time, returned to the Testing Stationwith improved products, able to stand the severe tests required. In thisway the Testing Station has been a most active agent in increasing thegeneral safety of explosives, and the manufacturers have shown clearlythat it never was their desire to offer inferior explosives to thepublic, but that their failures in the past were due solely to lack ofinformation in regard to the action of explosives under the conditionswhich exist before a mine disaster. The chance being offered toduplicate, at the Testing Station, the conditions represented in a minein the presence of gas, they showed an eagerness to modify and improvetheir explosives so as to enable them to answer severe miningconditions, which is most commendable to American industry. 

In regard to the unfavorable conditions existing in mines in the past, the same arguments may be used. In spite of the frequency of mineaccidents in the United States, and in spite of the high death rate incoal mining as compared with that in other countries, it must be said infairness that this has been the result of ignorance of the actualconditions which produce mine explosions, rather than any willfuldisregard of the known laws of safety by mine owners. Conditions inAmerican mines are far different from those obtaining in mines abroad, and, as a result, the rules which years of experience had taught toforeign colliery managers were not quickly applied to conditionsexisting in American mines; but, as soon as the work at the PittsburgStation had demonstrated the explosibility of the coal dust fromadjoining mines, and had shown the very great safety of some explosivesas compared with others, there was at once a readiness on the part ofmine owners throughout the country to improve conditions in their mines, and to take advantage of all the studies made by the Government, thusshowing clearly that the disasters of the past had been due to lack ofsufficient information rather that to any willful disregard of the valueof human lives. 

Another of the indirect benefits of the work of the Station has resultedfrom its examination of explosives for the Panama Canal. For severalyears the Isthmian Canal Commission has been one of the largest users ofexplosives in the world, and, in the purchase of the enormous quantitiesrequired, it was found necessary to establish a system of carefulexamination and inspection. This was done in order to insure the safetyof the explosives delivered on the Isthmus, and also to make certainthat the standards named in the contract were being maintained at alltimes. With its established corps of chemists and engineers, it wasnatural that this important work should be taken up by the TechnologicBranch of the United States Geological Survey, and, during the pastthree years, many millions of pounds of dynamite have been inspected andsamples analyzed by the chemists connected with the Pittsburg TestingStation, thus insuring the high standard of these materials. 

One of the many ways in which this work for the Canal Commission hasproved of advantage is shown by the fact that, as a result of studies atthe Testing Station, electric detonators are being made to-day which, inwater-proof qualities, are greatly superior to any similar product. Asthe improvements of these detonators were made by a member of thetesting staff, all the pecuniary advantages arising from them have gonedirectly to the Government, which to-day is obtaining superior electricdetonators, and at a cost of about one-third of the price of the formermaterials. 

All the work of the Technologic Branch is being carried out alongeminently practical lines, and is far removed from such work as can betaken up advantageously by private or by State agencies. The work of theMine Accidents Division was taken up primarily to reduce the number ofmine accidents, and to increase the general conditions of safety inmining. As the work of this Division has progressed, it has been foundto be of great advantage to the miner and the mine owner, while theultimate results of the studies will be of still greater value to everyconsumer of coal, as they will insure a continued supply of thisvaluable product, and at a lower cost than if the present methods, wasteful alike in lives and in coal, had been allowed to continue foranother decade. 

A. BARTOCCINI, Assoc. M. Am. Soc. C. E. (by letter). --The writer made apersonal investigation of the mine disaster of Cherry, Ill. Heinterviewed the men who escaped on the day of the accident, and alsoseveral of those who were rescued one week later. He also interrogatedthe superintendent and the engineer of the mine, and obtained all theinformation asked for and also the plans of the mine showing theprogress of the work. 

After a careful investigation the writer found that the followingconditions existed at the mine at the time of the disaster:

 _First. _--There were no means for extinguishing fires in the mine. 

 _Second. _--There were no signal systems of any kind. Had the mine been provided with electric signals and telephones, like some of the most modern mines in the United States, the majority of the men could have been saved, by getting into communication with the outside and working in conjunction with the rescuers. 

 _Third. _--The miners had never received instructions of how to behave in case of fire. 

 _Fourth. _--The main entries and stables were lighted with open torches. 

 _Fifth. _--The organization of the mine was defective in some way, for at the time of the disaster orders came from every direction. 

 _Sixth. _--The air shaft was used also as a hoisting shaft. 

 _Seventh. _--The main shaft practically reached only to the second vein; its extension to the third and deepest vein was not used. 

 _Eighth. _--Plans of the workings of the second and third veins were not up to date. The last survey recorded on them was that of June, 1909. This would have made rescue work almost impossible to men not familiar with the mine. 

 _Ninth. _--The inside survey of the mine was not connected with the outside survey. 

Would it not be possible for the United States Geological Survey toenforce rules which would prevent the existence of conditions such asthose mentioned? The Survey is doing wonderful work, as shown by therescue of twenty miners at Cherry one week after the conflagration; butthere is no doubt that perhaps all the men could have been saved iftelephone communications with the outside had been established. Telephone lines to resist any kind of a fire, can easily be installed, and the expense is small, almost negligible when one considers theenormous losses suffered by the mine owners and by the families of thevictims. 

H. G. STOTT, M. Am. Soc. C. E. --The curves shown by Mr. Wilson give aclear general idea of the relative efficiencies of steam and gas engineswhen treated from a purely theoretical thermodynamic point of view. Thispoint of view, however, is only justified when small units having amaximum brake horse-power not exceeding 1, 000 are considered. 

The steam engine or turbine operating under a gauge pressure of 200 lb. Per sq. In. , and with 150° superheat, has a maximum temperature of 538°Fahr. In its cylinder, while that of the gas engine varies between2, 000° and 3, 000° Fahr. 

The lubrication of a surface continually subjected to the lattertemperature would be impossible, so that water jackets on the cylindersand, in the larger units, in the pistons become absolutely necessary. Asthe cylinders increase in diameter, it is necessary, of course, toincrease their strength in proportion to their area, which, in turn, isproportional to the square of the diameter. The cooling surface, however, is only proportional to the circumference, or a single functionof the diameter. Increasing the strength in proportion to the square ofthe diameter soon leads to difficulties, because of the fact that theflow of heat through a metal is a comparatively slow process; the thickwalls of the cylinders on large engines cannot conduct the heat awayfast enough, and all sorts of strains are set up in the metal, due tothe enormous difference in temperature between the inside and the jacketlining of the cylinder. 

These conditions produce cut and cracked cylinders, with a naturalresultant of high maintenance and depreciation costs. These costs, insome cases, have been so great, not only in the United States, but inEurope and Africa, as to cause the complete abandonment of large gasengine plants after a few years of attempted operation. 

The first consideration in any power plant is that it shall bethoroughly reliable in operation, and the second is that it shall beeconomical, not only in operation, but in maintenance and depreciation. Therefore, in using the comparative efficiency curves shown in Mr. Wilson’s paper it should be kept in mind that the cost of power is notonly the fuel cost, but the fuel plus the maintenance and depreciationcharges, and that the latter items should not be taken from the firstyear’s account, but as an average of at least five years. 

The small gas engine is a very satisfactory apparatus when supplied withgood, clean gas, and when given proper attention, but great cautionshould be used before investing in large units, until furtherdevelopments in the art take place, as conservation of capital is justas important as conservation of coal. 

B. W. DUNN, Esq. [31] (by letter. )--The growing importance ofinvestigations of explosives, with a view to increasing the consumer’sknowledge of proper methods for handling and using them, is evident whenit is noted that the total production of explosives in the United Stateshas grown from less than 9, 000, 000 lb. In 1840 to about 215, 000, 000 lb. In 1905. Table 5 has been compiled by the Bureau of Explosives of theAmerican Railway Association. 

 TABLE 5. --Manufacture of Explosives in the United States, 1909. 

 ---------------------+-------------+------------------------------ Kind of explosives. | Number of | Maximum Capacity, in Pounds. | factories. +--------------+--------------- | | Daily. | Annual. ---------------------+-------------+--------------+--------------- Black powder | 49 | 1, 220, 150 | 366, 135, 000 High explosives | 37 | 1, 203, 935 | 361, 180, 500 Smokeless powders | 5 | 75, 686 | 22, 705, 800 ---------------------+-------------+--------------+---------------

The first problem presented by this phenomenal increase relates to thesafe transportation of this material from the factories to points ofconsumption. A package of explosives may make many journeys throughdensely populated centers, and rest temporarily in many widely separatedstorehouses before it reaches its final destination. A comprehensiveview of the entire railway mileage of the United States would show atany instant about 5, 000 cars partially or completely loaded withexplosives. More than 1, 200 storage magazines are listed by the Bureauof Explosives as sources of shipments of explosives by rail. 

The increase in the demand for explosives has not been due entirely tothe increase in mining operations. The civil engineer has been expandinghis use of them until now carloads of dynamite, used on the Isthmus ofPanama in a single blast, bring to the steam shovels as much as 75, 000cu. Yd. Of material, the dislodgment of which by manual labor would haverequired days of time and hundreds of men. Without the assistance ofexplosives, the construction of subways and the driving of tunnels wouldbe impracticable. Even the farmer has awakened to the value of thisconcentrated source of power, and he uses it for the cheap and effectiveuprooting of large stumps over extended areas in Oregon, while an entireacre of subsoil in South Carolina, too refractory for the plow, isbroken up and made available for successful cultivation by one explosionof a series of well-placed charges of dynamite. It has also been foundby experience that a few cents’ worth of explosive will be as effectiveas a dollar’s worth of manual labor in preparing holes for transplantingtrees. 

The use of explosives in war and in preparation for war is now almost anegligible quantity when compared with the general demand from peacefulindustries. With the completion of the Panama Canal, it is estimatedthat the Government will have used in that work alone more explosivesthan have been expended in all the battles of history. 

Until a few years ago little interest was manifested by the public insafeguarding the manufacture, transportation, storage, and use ofexplosives. Anyone possessing the necessary degree of ignorance, orrashness, was free to engage in their manufacture with incompleteequipment; they were transported by many railroads without any specialprecautions; the location of magazines in the immediate vicinity ofdwellings, railways, and public highways, was criticized only after somedisastrous explosion; and the often inexperienced consumer was withoutaccess to a competent and disinterested source of information such as henow has in the testing plant at Pittsburg so well described by Mr. Wilson. 

The first general move to improve these conditions is believed to havebeen made by the American Railway Association in April, 1905. Itresulted in the organization of a Bureau of Explosives which, throughits inspectors, now exercises supervision over the transportation of allkinds of dangerous articles on 223, 630 of the 245, 000 miles of railwaysin the United States and Canada. A general idea of the kind and volumeof inspection work is shown by the following extracts from the AnnualReport of the Chief Inspector, dated February, 1910:

 1909. 1908. “Total number of railway lines members of Bureau December 31st 172 158 Total mileage of Bureau lines December 31st 209, 984 202, 186 Total number of inspections of stations for explosives 6, 953 5, 603 Number of stations receiving two or more inspections for explosives 1, 839 1, 309 Total number of inspections of stations for inflammables 6, 950 1, 098 Number of stations receiving two or more inspections for inflammables 1, 886 .... Total number of inspections of factories 278 270 Number of factories receiving two or more inspections 75 69 Total number of inspections of magazines 1, 293 1, 540 Number of magazines receiving two or more inspections 349 361 Total number of boxes of high explosives condemned as unsafe for transportation 10, 029 4, 852 Total number of kegs of black powder condemned as unsafe for transportation 1, 468 531 Total number of cars in transit containing explosives inspected 475 448 Total number of cars in transit showing serious violations of the regulations 168 197 Total number of inspections of steamship companies’ piers (inflammable, 75; explosive, 63) 138 .... Total number of inspections made by Bureau 16, 087 8, 959 Total number of lectures to railway officials and employes and meetings addressed on the subject of safe transportation of explosives and other dangerous articles 215 171

 1909. 1908. 1907. “Total number of accidents resulting in explosions or fires in transportation of explosives by rail 12 22 79 Total known property loss account explosions or accidents in transporting explosives by rail $2, 673 $114, 629 $496, 820 Total number of persons injured by explosions in transit 7 53 80 Total number of persons killed by explosions in transit 6 26 52

 “During the same period reports have been rendered to the Chief Inspector by the Chemical Laboratory of the Bureau on 734 samples, as follows:

 Explosives 211 Fireworks 186 Inflammables 304 Paper for lining high explosive boxes 31 Ammunition 2 ---- Total 734

 “As a means of ensuring the uniform enforcement of the regulations, by a well grounded appreciation of their significance and application, the lectures delivered by representatives of the Bureau have proved most successful. The promulgation of the regulations is not of itself sufficient to ensure uniformity or efficiency in their observance, and so these lectures form a valuable supplement to the inspection service. They have been successfully continued throughout the year, and the requests for the delivery of them by the managements of so many of the membership lines, is a convincing testimonial of the high esteem in which they are held. 

 “While the lectures are primarily intended for the instruction and information of the officials and employes of the railway companies, and especially of those whose duties bring them into immediate contact with the dangerous articles handled in transportation, the manufacturers and shippers are invited, and they have attended them in considerable numbers. Many of this class have voluntarily expressed their commendation of the lectures as a medium of education, and signified their approval of them in flattering terms. 

 “The scope of these lectures embraces elementary instruction in the characteristics of explosives and inflammables and the hazards encountered in their transportation and in what respects the regulations afford protection against them. The requirements of the law, and the attendant penalties for violation, are fully described. Methods of preparation, packing, marking, receiving, handling and delivering, are explained by stereopticon lantern slides. These are interesting of themselves, and are the best means of stamping the impression they are intended to convey upon the minds of the audiences, and are always an acceptable feature of the lectures. The reception generally given to the lectures by those who have attended them, often at the voluntary surrender of time intended for rest while off duty, may be stated as an indication that the subject matter is one in which they are interested. 

 “The facilities of the Young Men’s Christian Association, in halls, lanterns and skilled lantern operators, have been generously accorded and made use of to great advantage, in connection with the lectures at many places. The co-operation of this Association affords a convenient and economical method of securing the above facilities, and the Association has expressed its satisfaction with the arrangement as in line with the educational features which they provide for their members. 

 “During the year 1909, 215 lectures were delivered at various points throughout the United States. ”

The Bureau of Explosives, of the American Railway Association, and theBureau of Mines, of the United States Geological Survey, wereindependent products of a general agitation due to the appreciation by alimited number of public-spirited citizens of the gravity of the“explosive” problem. It is the plain duty of the average citizen tobecome familiar with work of this kind prosecuted in his behalf. He maybe able to help the work by assisting to overcome misguided oppositionto it. Evidences of this opposition may be noted in the efforts of someshippers to avoid the expense of providing suitable shipping containersfor explosives and inflammable articles, and in the threats of miners’labor unions to strike rather than use permissible explosives instead ofblack powder in mining coal in gaseous or dusty mines. 

Too much credit cannot be given Messrs. Holmes and Wilson, and otherofficials of the Technologic Branch of the United States GeologicalSurvey, for the investigations described in this paper. They areestablishing reasonable standards for many structural materials; theyare teaching the manufacturer what he can and should produce, and theconsumer what he has a right to demand; with scientific accuracy theyare pointing the way to a conservation of our natural resources and to asaving of life which will repay the nation many times for the cost oftheir work. 

When these facts become thoroughly appreciated and digested by theaverage citizen, these gentlemen and their able assistants will have nofurther cause to fear the withdrawal of financial or moral support fortheir work. 

HERBERT M. WILSON, M. Am. Soc. C. E. (by letter). --The Fuel Division ofthe United States Geological Survey has given considerable attention tothe use of peat as a fuel for combustion under boiler furnaces, in gasproducers, and for other purposes. It is doubtless to this material thatMr. Allen refers in speaking of utilizing “marsh mud for fuel, ” since herefers to an address by Mr. Edward Atkinson on the subject of “Bog Fuel”in which he characterized peat by the more popular term “marsh mud. ”

In Europe, where fuel is expensive, 10, 000, 000 tons of peat are usedannually for fuel purposes. A preliminary and incomplete examination, made by Mr. C. A. Davis, of the Fuel Division of the Geological Survey, indicates that the peat beds of the United States extend throughout anarea of more than 11, 000 sq. Miles. The larger part of this is in NewEngland, New York, Minnesota, Wisconsin, New Jersey, Virginia, and otherCoastal States which contain little or no coal. It has been estimatedthat this area will produce 13, 000, 000, 000 tons of air-dried peat. 

At present peat production is in its infancy in the United States, though there are in operation several commercial plants which find aready market for their product and are being operated at a profit. Atest was made at the Pittsburg plant on North Carolina peat operated ina gas producer--the resulting producer gas being used to run a gasengine of 150 h. P. --the load on which was measured on a switch-board. Peat containing nearly 30% of ash and 15% of water gave 1 commercialhorse-power-hour for each 4 lb. Of peat fired in the producer. Had thepeat cost $2 per ton to dig and prepare for the producer, eachhorse-power-hour developed would have cost 0. 4 of a cent. The fuel costof running an electric plant properly equipped for using peat fuel, ofeven this low grade, in the gas producer would be about $4 per 100 h. P. Developed per 10-hour day. 

Equally good results were procured in tests of Florida and Michigan peatoperated in the gas producer. The investigations of peat under Mr. Davisinclude studies of simple commercial methods of drying, the chemical andfuel value, analyses of the peat, studies of the mechanical methods ofdigging and disintegrating the peat, and physical tests to determine thestrength of air-dried peat to support a load. 

The calorific value of peat, as shown by numerous analyses made by theUnited States Geological Survey, runs from about 7, 500 to nearly 11, 000B. T. U. , moisture free, including the ash, which varies from less than 2%to 20%, the latter being considered in Europe the limit of commercialuse for fuel. Analyses of 25 samples of peat from Florida, within theselimits as to ash, show a range of from 8, 269 to 10, 865 B. T. U. , only fourof the series being below 9, 000 B. T. U. , and four exceeding 10, 500B. T. U. , moisture free. Such fuel in Florida is likely to be utilizedsoon, since it only needs to be dug and dried in order to render it fitfor the furnace or gas producer. Many bituminous coals now usedcommercially have fuel value as low as 11, 000 B. T. U. , moisture free, andwith maximum ash content of 20%; buckwheat anthracite averages near thesame figures, often running as high as 24% ash. 

One bulletin concerning the peats of Maine has been published, andanother, concerning the peat industries of the United States, is incourse of publication. 

Mr. Bartoccini asks whether it would not be possible for the UnitedStates Geological Survey to enforce rules which would prevent theexistence of conditions such as occurred at the mine disaster of Cherry, Ill. 

The United States Government has no police power within the States, andit is not within its province to enact or enforce rules or laws, or evento make police inspection regarding the methods of operating miningproperties. The province of the mine accidents investigations and thatof its successor, the Bureau of Mines, is, within the States, like thatof other and similar Government bureaus in the Interior Department, theDepartment of Agriculture, and other Federal departments, merely toinvestigate and disseminate information. It remains for the States toenact laws and rules applying the remedies which may be indicated as aresult of Federal investigation. 

Investigations are now in progress and tests are being conducted with aview to issuing circulars concerning the methods of fighting mine fires, the installation of telephones and other means of signaling, and othersubjects of the kind to which Mr. Bartoccini refers. 

Much as the writer appreciates the kindly and sympathetic spirit of thediscussion of Messrs. Allen and Bartoccini, he appreciates even morethat of Colonel Dunn and Mr. Stott, who are recognized authoritiesregarding the subjects they discuss, and of Messrs. Kreisinger andSnelling, who have added materially to the details presented in thepaper relative to the particular investigations of which they havecharge in Pittsburg. 

Mr. Snelling’s reference to the use of explosives in blasting operationsshould be of interest to all civil engineers, as well as to miningengineers, as should Colonel Dunn’s discussion concerning the meansadopted to safeguard the transportation of explosives. 

Since the presentation of the paper, Congress has enacted a lawestablishing, in the Department of the Interior, a United States Bureauof Mines. To this Bureau have been transferred from the GeologicalSurvey the fuel-testing and the mine accidents investigations describedin this paper. To the writer it seems a matter for deep regret that theinvestigations of the structural materials belonging to and for the useof the United States, were not also transferred to the same Bureau. Onthe last day of the session of Congress, a conference report transferredthese from the Geological Survey to the Bureau of Standards. It isdoubtful whether the continuation of these investigations in thatBureau, presided over as it is by physicists and chemists of highscientific attainments, will be of as immediate value to engineers andto those engaged in building and engineering construction as they wouldin the Bureau of Mines, charged as it is with the investigationspertinent to the mining and quarrying industries, and having in itsemploy mining, mechanical, and civil engineers. 

FOOTNOTES

 [Footnote 1: Presented at the meeting of April 20th, 1910. ]

 [Footnote 2: “Coal Mine Accidents, ” by Clarence Hall and Walter O. Snelling. Bulletin No. 333, U. S. Geological Survey, Washington, D. C. ]

 [Footnote 3: “The Explosibility of Coal Dust, ” by George S. Rice and others. Bulletin No. * * *, U. S. Geological Survey. ]

 [Footnote 4: “Notes on Explosives, Mine Gases and Dusts, ” by Rollin Thomas Chamberlin. Bulletin No. 383, U. S. Geological Survey, 1909. ]

 [Footnote 5: “Prevention of Mine Explosions, ” by Victor Watteyne, Carl Meissner, and Arthur Desborough. Bulletin No. 369, U. S. Geological Survey. ]

 [Footnote 6: With a view to obtaining a dust of uniform purity and inflammability. ]

 [Footnote 7: “The Primer of Explosives, ” by C. E. Munroe and Clarence Hall. Bulletin No. 423, U. S. Geological Survey, 1909. ]

 [Footnote 8: “Tests of Permissible Explosives, ” by Clarence Hall, W. O. Snelling, S. P. Howell, and J. J. Rutledge. Bulletin No. * * *, U. S. Geological Survey. ]

 [Footnote 9: “Structural Materials Testing Laboratories, ” by Richard L. Humphrey, Bulletin No. 329. U. S. Geological Survey, 1908; “Portland Cement Mortars and their Constituent Materials, ” by Richard L. Humphrey and William Jordan, Jr. , Bulletin No. 331, U. S. Geological Survey, 1908; “Strength of Concrete Beams, ” by Richard L. Humphrey, Bulletin No. 344, U. S. Geological Survey, 1908. ]

 [Footnote 10: “Fire Resistive Properties of Various Building Materials, ” by Richard L. Humphrey, Bulletin No. 370, U. S. Geological Survey, 1909. ]

 [Footnote 11: “Purchasing Coal Under Government Specifications, ” by J. S. Burrows, Bulletin No. 378, U. S. Geological Survey, 1909. ]

 [Footnote 12: “Experimental Work in the Chemical Laboratory, ” by N. W. Lord, Bulletin No. 323, U. S. Geological Survey, 1907: “Operations of the Coal Testing Plant, St. Louis, Mo. ” Professional Paper No. 48, U. S. Geological Survey, 1906. ]

 [Footnote 13: Also Bulletins Nos. 290, 332, 334, 363, 366, 367, 373, 402, 403, and 412, U. S. Geological Survey. ]

 [Footnote 14: “Tests of Coal for House Heating Boilers, ” by D. T. Randall, Bulletin No. 336, U. S. Geological Survey, 1908. ]

 [Footnote 15: “The Smokeless Combustion of Coal, ” by D. T. Randall and H. W. Weeks, Bulletin No. 373, U. S. Geological Survey, 1909. ]

 [Footnote 16: “The Flow of Heat through Furnace Walls, ” by W. T. Ray and H. Kreisinger. Bulletin (in press), U. S. Geological Survey. ]

 [Footnote 17: The assumption is made that a metal tube free from scale will remain almost as cool as the water; actual measurements with thermo-couples have indicated the correctness of this assumption in the majority of cases. ]

 [Footnote 18: “Heat Transmission into Steam Boilers, ” by W. T. Ray and H. Kreisinger, Bulletin (in press), U. S. Geological Survey. ]

 [Footnote 19: “The Producer Gas Power Plant, ” by R. H. Fernald, Bulletin No. 416, U. S. Geological Survey, 1909; also Professional Paper No. 48 and Bulletins Nos. 290, 316, 332, and 416. ]

 [Footnote 20: A Taylor up-draft pressure producer, made by R. D. Wood and Company, Philadelphia, Pa. ]

 [Footnote 21: “Coal Testing Plant, St. Louis, Mo. , ” by R. H. Fernald, Professional Paper No. 48, Vol. III, U. S. Geological Survey, 1906. ]

 [Footnote 22: A report of these tests may be found in Bulletin No. * * *, U. S. Geological Survey. ]

 [Footnote 23: “Illuminating Gas Coals, ” by A. H. White and Perry Barker, U. S. Geological Survey. ]

 [Footnote 24: “Gasoline and Alcohol Tests, ” by R. M. Strong, Bulletin No. 392, U. S. Geological Survey, 1909. ]

 [Footnote 25: “Washing and Coking Tests, ” by Richard Moldenke, A. W. Belden and G. R. Delamater, Bulletin No. 336, U. S. Geological Survey, 1908; also, “Washing and Coking Tests at Denver, Colo. , ” by A. W. Belden and G. R. Delamater, Bulletin No. 368, U. S. Geological Survey, 1909. ]

 [Footnote 26: U. S. Geological Survey, Professional Paper No. 48, Pt. III, and Bulletins Nos. 290, 332, 336, 368, 385, and 403. ]

 [Footnote 27: Professional Paper No. 48, and Bulletins Nos. 290, 316, 332, 343, 363, 366, 385, 402, 403, and 412, U. S. Geological Survey. ]

 [Footnote 28: “Peat Deposits of Maine, ” by E. D. Bastin and C. A. Davis. Bulletin No. 376, U. S. Geological Survey, 1909. ]

 [Footnote 29: U. S. Geological Survey, Pittsburg, Pa. ]

 [Footnote 30: Chief Explosives Chemist, U. S. Geological Survey. ]

 [Footnote 31: Lieutenant-Colonel, Ordnance Dept. , U. S. A. ]

 * * * * * * * * * * * * * *

[Errata:

 [Fig. 3. Caption] SAFETY LAMP TESTING GALLERY _text reads “SAFTY”_

 [Mine-Rescue Training] experienced in rescue operations and familiar / with the conditions existing after mine disasters _text reads “familar”_

 so as to determine, if possible, the progress of combustion (Fig. 1, Plate XVIII). _text reads “Pate XVIII”_

 The chemical analyses of the coals _text reads “anaylses”_ ]