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AMERICAN HAND BOOK

OF THE

DAGUERREOTYPE

GIVING

THE MOST APPROVED AND CONVENIENT

METHODS FOR PREPARING THE CHEMICALS, AND

THE COMBINATIONS USED IN THE ART. 

CONTAINING THE

DAGUERREOTYPE, ELECTROTYPE, AND VARIOUS OTHER PROCESSES EMPLOYED IN TAKING

HELIOGRAPHIC IMPRESSIONS. 

BY

S. D. HUMPHREY

FIFTH EDITION

NEW YORK:

PUBLISHED BY S. D. HUMPHREY

37 LISPENARD STREET

1858

Entered, according to Act of Congress, in the year 1858, by S. D. HUMPHREY, In the Clerk's Office of the District Court of the SouthernDistrict of New York. 

To J. GURNEY, WHOSE PROFESSIONAL SKILL, SCIENTIFIC ACCURACY, ANDENERGETIC PERSEVERANCE, HAVE WON FOR HIM UNIVERSAL ESTEEM, THIS WORK ISMOST RESPECTFULLY INSCRIBED. 

PREFACE. 

There is not an Amateur or practical Daguerreotypist, who has not feltthe want of a manual--Hand Book, giving concise and reliableinformation for the processes, and preparations of the Agents employedin his practice. 

Since portraits by the Daguerreotype are at this time believed to bemore durable than any other style of "Sun-drawing, " the author has hitupon the present as being an appropriate time for the introduction ofthe Fifth Edition of this work. The earlier edition having a longsince been wholly; exhausted, the one now before you is presented. 

The endeavor has been to point out the readiest and most approvedMethods of Operation, and condense in its pages; as much practicalinformation as its limits will admit. An extended Preface isunnecessary, since the aim and scope of this work are sufficientlyindicated by the title. 

S. D. HUMPHREY NEW YORK, 1858. 

CONTENTS

CHAPTER I. 

Polishing the Daguerreotype Plate--Buffing the Plate--Coating thePlate--Exposure of the Plate in the Camera--Position Developing theDaguerreotype--Exposure to Mercury--Removing the Coating--Gilding orfixing the Image--Coloring Daguerreotype, . . . . . 18

CHAPTER II. 

Coloring Back Grounds--Transparent ditto--Gilding Dissolvent--Solutionfor removing Specks--Solarized Impression--To Purify Water--CleaningMercury--Adhesive Paper--Black Stain for Apparatus--Sealing Wax forBottles--Rouge--Rotten Stone--Potassa Solution--HyposulphiteSolution--Substitute for do. --Gilding Solution--Solution for increasingthe Brilliancy of the Daguerreotype--Bleaching Solution;--ColdGilding--Neutralizing Agents--Buff Dryer--Keeping Buffs inorder--Cleaning Buckskins--Reflector for taking Views, . . . . 52

CHAPTER III. 

Bromine and its Compounds--Iodine and its Compounds--Chlorine and itsCompounds--Cyanide of Potassium--Hyposulphite of Soda--Hyphosulphite ofGold--Nitric Acid--Nitro-Muriatic Acid--Hydrochloric Acid--HydrofluoricAcid--Sulphuric Acid--Accelerating Substances--Liquid Sensitives--DrySensitives, etc. , etc. , . . . . . 72

CHAPTER IV. 

Light--Optics--Solar Spectrum--Decomposition of Light--Light, Heat, andActinism--Blue Paper and Color for the Walls of the OperatingRoom--Proportions of Light, Heat and Actinism composing aSunbeam--Refraction--Reflection--Lenses--Copying SphericalAberration--Chromatic Aberration, . . . 131

CHAPTER V. 

To make Plates for the Daguerreotype--Determining the Time of Exposurein the Camera--Instantaneous Process for ProducingDaguerreotype--Galvanizing the Daguerreotype Plate--SilveringSolution--Daguerreotype without Mercury--Management of Chemicals--Hintsand Cautions--Electrotyping--Crayon Daguerreotypes--IlluminatedDaguerreotypes--Natural Colors in Heliography--MultiplyingDaguerreotypes on one Plate--Deposit in Gilding--Practical Hints on theDaguerreotype, . . . 149

CHAPTER VI. 

An Account of Wolcott and Johnson's Early experiments in theDaguerreotype, . . . 188

AMERICAN HAND-BOOK of THE DAGUERREOTYPE. 

CHAPTER I. 

Polishing the Daguerreotype Plate--Buffing the Plate--Coating thePlate--Exposure of the Plate in the Camera--Position--Developing theDaguerreotype--Exposure to Mercury--Removing the Coating--Gilding orfixing the Image--Coloring Daguerreotype. 

Polishing the Daguerreotype Plate. --I shall endeavor to present to thereader the process I have found productive of good and satisfactoryresults, presenting the same in a clear and concise manner, so that anyone, by following the various manipulations given, will be enabled tosucceed. If there is any one part of the process in Daguerreotype inwhich operators fail more than all others, it is in not properlypreparing the plate. It has truly been said that it would take avolume to describe all the methods that have been suggested forpolishing the plate. 

I shall confine myself to the following description, which has beensuccessfully practised, also most generally adopted by our operators, and I believe equal, if not superior to any other method, yet at thesame time it is not of so much importance what particular method isemployed, so that it be thoroughly and skillfully carried out. 

There is a general tendency with beginners to slight this operation;hence the necessity of adopting a system which precludes thepossibility of doing so. During many years' study and practice in theart, I have tried numerous methods and substances for the betteraccomplishment of the end in view, and have finally settled upon thefollowing, as being (so far as experience allows me to Judge) the modusoperandi, best suited to all circumstances; under no condition would Iapprove of a method less rigorous or precise. 

The operator being provided with a bottle of finely prepared rottenstone, cover the mouth of the bottle with a piece of thick paper, thisperforated with a pin so that the rotten stone can be dusted on theplate. Fasten the plate on the holder, take the rotten stone (Becker'scan always be depended upon), and dust on lightly until the surface isfreely covered; now drop on the plate's surface a few drops of analcoholic solution. *

* This solution is composed of equal parts of alcohol and water, forthe summer, and in winter three parts alcohol to one of water; a fewdrops of potassa solution may be added, and is known to have a decidedeffect upon the plate. 

Take a patch of Canton flannel; in order to prevent the moisture fromthe hand it should have a thick, firm texture: with this rub the platein circles across, then back covering one-half of the former row ofcircles in each crossing until you have gone over the plate and back tothe point of beginning, occupying at least half a minute in theoperation, for a small plate, and so in proportion for the other sizes. 

Care should be observed to keep the patch wet with the alcoholicsolution forming a paste on the surface of the plate; the motion of thehand should be brisk and free, not hurried, and the pressure aboutequal to that of a pound weight. When the cotton is disposed to adhereto the plate, and slip from under the finger, spread the fore andmiddle fingers a little apart, then pressing down, bring them togetherin such a manner as to form a fold in the cloth between them, by whichmeans you will hold it perfectly secure. 

Avoid wetting the fingers, and should they perspire, wipe them often, as the moisture penetrating the cotton and coming in contact with theplate, would cause streaks it would be difficult to remove. I willhere remark that many operators use much more cotton flannel than thereis need of. I have found in my experience that a single patch, aboutone and half inch square, will be better for cleaning a number ofplates than a new piece for every plate. This is the case for the wet, and for the dryrubbing two or three pieces will be found to answer. Thus with four or five cloths a dozen plates may be prepared. 

Some operators use prepared cotton, and think it more convenient thanthe flannel. This may be had prepared free from seeds and in a veryperfect state, if wished. 

In going over the plate, great care should be observed, in touching itssurface as equally as possible. The greatest care should be takenneither to touch the plate with the fingers, nor that part of thecotton flannel which is to come in contact with its surface; take aclean piece of flannel by one corner, snap it smartly to free it fromdust and loose fibres, lay it face-side upward, dust on a little finerotten stone; with this, polish around, or across, or in circles, lightly and briskly, passing gradually over the whole surface of theplate, as was done before with the wet. The plate should now exhibit abright, clear, uniform surface, with a strong metallic lustre, perfectly free from any appearance of film; if not, the last polishedshould be continued until the effect is obtained, and when onceobtained, the plate is ready for buffing. 

Buffing the Plate. --There are a variety of ways and means employed inthis part of the operation. Some choose wheels, and others prefer theordinary hand-buff. I have been unable to detect any peculiar advantagein the use of the wheel except in the facility of the operation; nodoubt, however, but there is a saving of time, particularly in thepreparation of the larger plates. For general use, we have not seen awheel better adapted for this purpose than the one patented by Messrs. Lewis. 

It is generally well to use a hand-buff before placing the plate on thewheel; this is in order to prevent, as far as possible, the dust orother substance that may be on the surface of the plate from coming incontact with the cover of the wheel. I will here follow out the use ofthe hand-buffs (two are necessary) as they are mostly used. 

In the morning, before using the buffs, brush both as clean aspossible, in order to free them from dust; then with the blade of apair of shears, held perpendicular, rub the buffs from end to end; thenknock them both together in order to free them from all dust or othersubstances, occasionally exposing them to the sun or to the fire. 

With one of the buffs (reserving the finest and softest for the lastoperation), powder its face with fine rouge and brush off slightly, leaving only the finest particles in it. Every operator should havetwo plate-holders; one for cleaning and one for buffing the plate; forwhen using only one, the rotten stone is liable to get on the buff andscratch the plate. 

Rest the fingers of the left hand on the back of the buff, near thefarther end, with about the same pressure as in cleaning, while withthe right you bear on the handle to correspond, and give the buff afree, easy, horizontal motion, passing it very nearly the whole lengthover the plate each time. Continue this operation in such a mannerthat the plate will on all parts of its surface have received an equalamount of polish. This buff once well filled with polish, add butlittle after, say a small quantity once in two or three plates. Thepolish as well as the buffs must be kept perfectly dry. 

The second buff should always be in the best order, and if this is thecase, but little polish after the first need be used. Much dependsupon the last finish of the surface of the plate, and as a fineimpression is desired in the same ratio, the operator must exercisecare and skill in this operation. Some buff the smaller plates on thehands, by resting them on the fingers in such a manner that the buffcannot touch them; some by holding the edges with thumb and littlefinger, with the remaining fingers under, or on the back; and othersbuff on the holder. When this last method is adopted, it requires thegreatest caution to prevent the dust from getting on the buff. Theholder should be wiped clean. 

The plate frequently slips off or around, and the buff comes in contactwith the bed of the holder. When, however, the operator is sounfortunate as to meet with this mishap, the utmost care must beobserved in thoroughly cleaning the buff cover before further buffing. In this last buffing it may be continued as before, except without theapplication of polish powder to the last buff. Examine the surfaceoccasionally, and buff more lightly towards the close of the operation, using at last the mere weight of the buff. This last buffing shouldoccupy as long a time as the first. 

The point to be aimed at is, the production of a surface of suchexquisite polish as to be itself invisible, like the surface of amirror. The secret of producing pictures discernible in any light, lies in this: the more dark, deep and mirror-like the surface of theplate, the more nearly do we approach to perfection. 

In all cases, very light and long continued buffing is productive ofthe greater success, since by that means a more perfect polish can beobtained. 

The question is often asked, why is it that the plates receive thecoating so unevenly? I will answer by saying that it may arise fromtwo causes: the first and most general cause is that those parts of theplate's surface which will receive the heaviest coating have been morethoroughly polished, and the consequence is that it is more sensitiveto the chemical operation; second, and might perhaps be considered apart of the first, the heat of the plate may not be equal in all itsparts; this may arise from the heat caused by the friction in buffing. It is a well known fact, with which every observing practitioner isfamiliar, that a silver plate at a temperature of 45 deg. Or less, exposed to the vapors of iodine, is less sensitive and takes a longertime to coat, than when it is at a temperature of 60 deg. Or more. 

Whenever a view is to be taken, or any impression which requires theplate to be turned on the side, it should be buffed in the otherdirection, so that the marks will always be horizontal, when thepicture is in position. With the finest possible polish, the plate isready for the coating box. 

The question is often asked by operators, what is the state of theplate when polished and allowed to stand for a time before using? Tomeet this point we hare only to consider the silver and the poweracting upon it. Pure atmosphere does not act upon silver; but we donot have this about in our operating rooms, as it is more or lesscharged with sulphurated hydrogen, which soon tarnishes the surface ofthe plate with a film of brown sulphurate. It is this that sometimescauses the specks which appear on finishing the impression, and are agreat annoyance. Hence we see that the plate should be buffed justbefore receiving the vapor of iodine. Mr Hunt gives his opinion of theuse of diluted nitric acid as the best solution for freeing, thesurface of the plate; he says:

"Numerous experiments on plated copper, pure silver plates, and onsilvered glass and paper, have convinced me that the first operation ofpolishing with nitric acid, etc. , is essential to the production of themost sensitive surface. All who will take the trouble to examine thesubject, will soon be convinced that the acid softens the silver, bringing it to a state in which it is extremely susceptible of beingeither oxydized or iodized, according as the circumstances may occur ofits exposure to the atmosphere or the iodine. "

I cannot see the objection to this solution; not, however, in generaluse. Our operators do not find it of sufficient importance to thesuccess of their pictures to accept it, the alcoholic solution being inits nature less objectionable. 

I will say here, that a plate submitted to only an ordinary polish isfound to contain numberless minute particles of the powder made use of. Should the same plate be buffed for a long time, the polish will nearlyall disappear, leaving the cavities in the surface free for the actionof agents employed in subsequent operation. For this reason, I findthat great amount of polishing powder should not be applied to the lastbuff, and it is obvious that three buffs can be employed to adventure;the two last should not receive any polishing materials. I haveexamined a plate that was considered to possess a fine finish, andsimilar had produced good impressions; these same plates, whensubjected to a long and light buffing, would present a surface no finerin appearance to the naked eye; but upon exposure to the solarradiation, would produce a well-defined image in one fourth less timethan the plate without the extra buffing. 

Coating the Plate. --For this purpose our mechanics and artists haveprovided a simple apparatus called a coating-box, which is so arrangedas to be perfectly tight, retaining the vapor of the iodine oraccelerators, and at the same time allowing, by means of a slide, theexposure of the plate to these vapors. They can readily be obtained byapplication to any dealer, all of whom can furnish them. 

The principal difficulty in coating the plate, is that of preservingthe exact proportion between the quantity of iodine and bromine, orquick. It is here necessary to say, that hardly any two persons seealike the same degree of color, so as to be enabled to judge correctlythe exact tint, i. E. What one might describe as light rose red, mightappear to another as bright or cherry red; consequently, the only rulefor the student in Daguerreotype, is to study what appears to him to bethe particular tint or shade required to aid him to produce the desiredresult. Practise has proved that but a slight variation in thechemical coating, of the Daguerreotype plate will very materiallyaffect the final result. 

The operator will proportion the coating of iodine and bromine oraccelerators according to the strength and composition of the latter. 

Experience proves that the common impressions, iodized to a ratherlight yellow gold tint, and brought by the bromine to a very light, rose color, have their whites very intense, and their deep shades veryblack. It is also known that if you employ a thicker coating of iodineand apply upon it a proportionate tint of bromine, so as to obtain adeep rose tint, delineations will be less marked, and the image have asofter tone. This effect has been obvious to everyone who haspractised the art. Thus I may observe that the light coatings producestrong contrast of light and shade, and that this contrast growsgradually less, until in the very heavy coating it almost whollydisappears. From this it will readily be perceived that the middleshades are the ones to be desired for representing the harmoniousblending of the lights and shades. 

Then, if we examine, with respect to strength, or depth of tone, andsharpness of impression, we see that the light coating, produces a verysharp but shallow impression; while the other extreme gives a deep butvery dull one. Here, then, are still better reasons for avoidingeither extreme. The changes through which the plate passes in coatingmay be considered a yellow straw color or dark orange yellow, a rosecolor more or less dark in tint, or red violet, steel blue or indigo, and lastly green. After attaining this latter color, the plate resumesa light yellow tint, and continues to pass successively a second time, with very few exceptions, through all the shades above mentioned. 

I will here present some excellent remarks upon this subject by Mr. Finley. This gentleman says:

"It is well known to all who have given much attention to the subject, that an excess of iodine gives the light portions of objects withpeculiar strength and clearness, while the darker parts are retarded, as it were, and not brought out by that length of exposure whichsuffices for the former. Hence, statuary, monuments, and all objectsof like character, were remarkably well delineated by the originalprocess of Daguerre; the plate being coated with iodine alone. Anexcess of bromine, to a certain degree, has the opposite effect; thewhite portions of the impression appearing of a dull, leaden hue, whilethose which should be black, or dark, appear quite light. This beingthe case, I conclude there must be a point between the two extremeswhere light and dark objects will be in photogenic equilibrium. Thegreat object, therefore, is to maintain, as nearly as possible, aperfect balance between the two elements entering into union to formthe sensitive coating of the plate, in order that the lights and shadesbe truly and faithfully represented, and that all objects, whetherlight or dark, be made to appear so far conformable to nature, as isconsistent with the difference in the photogenic energy of thedifferent colored rays of light. It is this nicely-balancedcombination which ensures, in the highest degree, a union of theessential qualities of a fine Daguerreotype, viz. , clearness andstrength, with softness and purity of tone. 

"So far as I know, it is the universal practice of operators to judgeof the proportion of iodine and bromine in coating the plate, by twostandards of color the one fixed upon for the iodine, the other for theadditional coating of bromine. Now I maintain that these alone form avery fallacious standard; first, because the color appears to the eyeeither lighter or darker, according as there is more or less light bywhich we inspect the coating; and secondly, because if it occur that weare deceived in obtaining the exact tint for the first coating, we areworse misled in obtaining the second, for if the iodine coating be toolight, then an undue proportion of bromine is used in order to bring itto the second standard, and vice versa. "

The iodine box should be kept clean and dry. The plate immediatelyafter the last buffing, should be placed over the iodine, and thecoating will depend upon the character of the tone of the impressiondesired. Coating over dry iodine to an orange color, then over theaccelerator, to a light rose, and back over iodine one sixth as long asfirst coating, will produce a fine, soft tone, and is the coatinggenerally used for most accelerators. The plate iodized to a darkorange yellow, or tinged slightly with incipient rose color, coatedover the accelerator to a deep rose red, then back over iodineone-tenth as long as at first coating, gives a clear, strong, bold, deep impression. 

I will here state a singular fact, which is not generally known to theoperator. If a plate, coated over the iodine to a rose red, and thenexposed to strong dry quick or weak bromine water, so that a change ofcolor can be seen, then recoated over the iodine twice as long as atfirst coating, it will be found far more sensitive when exposed to thelight than when it has been recoated over the iodine one-fourth of thetime of the first coating. 

Probably the best accelerating combination is the American compoundformerly known as "Gurney's American compound, " or some of thecombinations of bromide of lime. The first is thought to possessperhaps more uniformity in its action than any other combination I haveever used. 

The plate once coated should be kept excluded from the light by meansof the plate holder for the camera box. 

I will notice one of the principal causes having a tendency to preventthe perfect uniformity of chemical action, between the iodine andsilver; hydrogen, or the moisture in the atmosphere, makes a veryperceptible barrier. This moisture may arise as the result of thecold, from a want of friction in the buffing of the plate, which, coming in contact with the warmer air, as a writer on this subject says:

"It is well known that as often as bodies, when cold, are exposed to awarmer air, the humidity contained in them is condensed. It is to thiseffect that we must attribute the difficulty experienced in operatingin most cases. " This is corroborated by the results experienced by ouroperators. So it is seen that the plate should be of a temperatureabove that of the atmosphere. Mr. Gurney submits his plates to agentle heat from a spirit lamp just before exposing them to the vaporof iodine. Experience has convinced me that a plate heated to about 80deg. Before being exposed to iodine will present a far better definedimage than a plate at a temperature of 50 deg. I account for this bynoticing that, at a higher temperature, the plate throws off any largercrystals that might otherwise be deposited, receiving only the finer, thus producing a more perfect chemical combination of iodide of silver. I would call the attention of the operator to this point, as presentingsomething of interest, and which may direct in a way of acceleratingthe future operations. 

That the presence of a film of moisture over the plate is a preventiveof uniform chemical action, may be readily understood from the factthat iodine is almost insoluble in water, requiring seven thousandparts of water to dissolve one of iodine, or one grain to a gallon ofwater. Yet its affinities for silver and other substances are sopowerful as to prevent its existing in an insulated state, hence we canaccount for the frequent occurrence of a plate presenting parts of animage over its surface. It is quite evident that those parts ofplate's surface covered with moisture are nothing like as sensitive tothe iodine as those parts perfectly free. 

Exposure of the plate in the Camera, and Position. --The time ofexposure necessary to produce an image upon the Daguerreotype plate, can only be determined by experiment, and requires a liberality ofjudgment to be exercised on the part of the operator. The constantvariation of the light renders it impossible to lay down any exact ruleupon this point. Light is not alone to be considered; the amount ofcoating exercises a deviating influence, also the subjects to berepresented are not equally photogenic, some requiring much longer timeof exposure than others. This may be easily observed by exposing theplate at the same time to a plaster bust and a piece of black velvet, the first being a much stronger reflector of light than the latter: thetime necessary to produce a well developed image of the velvet beingabout six times longer than that required to produce an equally definedimage of plaster. The manner of judging correctly of the time is bythe appearance of impression after it has been developed by themercurial vapors. Should it present a deep blue or black appearance itis solarized or over-timed. This sometimes is to an extent, that aperfect negative is formed, the white being represented black, and thedark light. 

An object requiring the particular care and attention of the operatoris the proper focus. It is not unfrequently the complaint of sittersthat their hands are represented as being magnified and greatly out ofproportion with the general figure. This is the case also with thenose and eyes, but in a less degree. As this cannot be whollyremedied, it is desirous to come as near as possible, and in order todo this, it is necessary to present the figure in such a position as tobring it as nearly as possible upon the same plane by making all partsnearly at equal distance from the lenses. This must be done by thesitter inclining the head and bust formed to a natural, easy position, and placing the hands closely to the body, thus preserving a propelproportion, and giving a lively familiarity to the general impression. It is not an uncommon fault among our less experienced operators togive a front view of the face of nearly every individual, regardless ofany particular form, and this is often insisted upon by the sitter, *who seems to think the truth of the picture exists principally in theeyes staring the beholder full in the face. 

* I might here picture some curious scenes experienced by our operatorsEvery one is familiar with a certain class of our community whose ideasof the importance of a free and easy position of the body are tooclosely confined with stays, attention to toilet, tightly fitting dresscoats and the like, to admit of being represented as if nature hadendowed them with least possible power of flexibility. To such wewould suggest the following, to be well learned and retained in themind while presenting themselves before the Daguerreotype camera:

"The experience of one who has often been Daguerreotyped, is, to letthe operator have his own way. "

Nothing, in many instances, can be more out of place in a Daguerreotypeportrait than this, for let a man with a thin, long, defeated-politician-face, be represented by a directly front view, wehave, to all appearances, increased the width of the face to such anextent as to reveal it flat and broad, losing the characteristic pointby which it would be the most readily recognized. The method we shouldadopt in taking the likeness of such an individual as above, would beto turn the face from the camera, so as to present the end of the noseand the prominence of the cheek bone equally distant from the lenses, and then focusing on the corner of the eye towards the nose, we cannotin many cases, fail to produce an image with the lips, chin, hair, eyesand forehead in the minutest possible definition. 

It should be the study of every operator to notice the effect of thelights and shades while arranging the sitter, and at the same time bevery particular to give ease in the position. 

No matter how successful the chemical effect may have been, should theimage appear stiff and monument-like, all is lost. "In themasterpiece, grace and elegance must be combined. "

I will here use the words of another, which are very true:

"So great is the difference in many faces, when inspected in oppositedirections, that one of the two views, however accurately taken, wouldnot communicate the likeness--it not being, the usually observedcharacteristic form. When the right view of the head is obtained, itis first necessary to consider the size of the plate it is to be takenon, so as to form an idea of the proportion the head should bear to it. The mind must arrange these points before we commence, or we shall findeverything, too large or too small for the happy proportion of thepicture, and the conveying of a just notion of the stature. The workwill have to be done over, and time sacrificed, if this is not attendedto. The adjustment of the head to the size of the plate (as seen fromthe margin of the mat), is not to be taught: everyone must bringhimself, by scrutinizing practice, to mathematical accuracy; forsomething will be discovered in every face which can be surmounted onlyby experience. 

"The eye nearest the camera, in a three-quarter-face, is placed in themiddle of the breadth of the plate; the chin, in a person of middlestature, in the middle of the length, and higher according to theproportional height of the person. "

In regard to the proper elevation of the camera, it may be here statedthat I have found it best in taking portraits where the hands areintroduced, to place the camera at about equal height with the eyes ofthe sitter, in order to bring the face and hands equi-distant from thetube. It will be found, if the above be followed, that by attaching astring to the camera tube, and making a semi-circle, that the face andhands of the sitter will occupy a corresponding distance, and theconsequence is that the impression will appear without the hands beingmagnified. It has been found that a person with a freckly face canhave as fine, fair, and clear an impression as the most perfectcomplexion; this may be done by the subject rubbing the face until itis very red. The effect is to lessen the contrast, by giving thefreckles and skin the same color and the photogenic intensity of thered and yellow being nearly the same, an impression can be producedperfectly clear. 

When a child is to be taken, and there are doubts of its keeping still, the operation may be accelerated by placing it nearer the windowbringing the screen nearer, and placing a white muslin cloth over thehead; this will enable you to work in one third of the usual time. Should the person move, or the plate become exposed to the light, itmay be restored to its original sensitiveness by placing it over thequick, one or two seconds. 

Developing the Daguerreotype. --After the plate has been submitted tothe operation of the light, the image is still invisible. It requiresto be exposed to the vapors of heated mercury. It is not absolutelynecessary to apply artificial heat to the mercury to develop the image, for fair proofs have been produced by placing a plate over the bath atthe ordinary temperature of the atmosphere. This plan, however, requires a long time and cannot be adopted in practice, even if it wereadvisable. The time more usually required in developing the image overthe mercurial vapors, is about two minutes, and the temperature israised to a point necessary to produce the desired effect in that time. This point varies as indicated by different scales, but for theordinary scales it is not far from 90 deg. Cen. 

The mercury bath is accompanied with a centigrade thermometer, by whichthe heat is regulated. Those furnished by the manufacturers are notalways correct, and it requires some experience to find the properdegree on the scale. 

I would here remark that it is advisable, when placing the spirit lampunder the bath, to so arrange it that the position of applied heatshould always be on the same point, viz. , should the heat be directlyunder the bulb containing the thermometer it would raise the mercury inthe tube to the point marked, and the temperature of that in the bathwould be far below what it should be; hence it is (where time isfollowed for developing) that many failures occur. This is observedmore readily in the large baths made of thick iron, particularly uponfirst heating. In practice I apply the heat as nearly as possiblebetween the centre of the bottom of the bath and the bulb containingthe mercury tube. It is advisable to keep the lamp lighted under thebath from the time of commencing in the morning to the close ofbusiness at night. By this means you have a uniformity of action, thatcannot be otherwise obtained. 

It is well known to the experienced Daguerreotypist, that differentatmospheres have a decided effect upon the mercury in developing theDaguerreotype. It will require a greater degree of heat for oneatmosphere than for another. Experience alone determines this littledifference. 

In summer, on cloudy and stormy days, mercurial vapors rise morereadily and quickly than in the temperature of autumn or winter. From60 degrees upwards towards the boiling point (660 deg. ), the vapors ofmercury rise in greater abundance and collect in larger globules oncold surfaces. 

For various reasons I prefer a high temperature and short exposure. Itaccelerates the process. It renders the lights of the picture morestrong and clear, while the deep shades are more intense. It gives afiner lustre to the drapery. The solarized portions also are veryseldom blue, especially after gilding. If heated too high, however, the light parts become of a dead, chalky white, and the shadows areinjured by numerous little globules of mercury deposited over them. Just the right quantity of mercury leaves the impression of atransparent, pearly white tone, which improves in the highest degree ingilding. To mercurialize with exactness is a nice point. If there isreason to suspect having timed rather short in the camera, reduce thetime over mercury in a corresponding proportion. A dark impressionwill be ruined by the quantity of mercury which would only improve alight one. 

If practicable, it is most expedient that the plate be submitted to theaction of mercury immediately on coming from the camera. I havefrequently, however, carried plates for miles in the plate-holders andafter exposing in the camera, brought them back to expose to mercury, and obtained fair proofs; but for the reason before given, it isadvisable to carry along the bath, and bring out the impression on thespot. 

It is sometimes the practice of inexperienced operators to take theplate off the bath and examine the impression by solar light. Thisplan should be abandoned, as it is almost sure to produce a dense bluefilm over the shadows. 

This I am led to believe is occasioned by the action of light on theyet sensitive portions of the plate, and made to appear only bysubsequent exposure to mercury, being equivalent to solarization. 

There has been little said by our professors upon the subject of theposition of the plates while exposed to the mercurial vapour. Mr. Hunt, in referring to this subject, says: "Daguerre himself laid muchstress upon the necessity of exposing the plate to the mercury at anangle of about 45 deg.. This, perhaps, is the most convenient positionas it enables the operator to view the plate distinctly, and watch thedevelopment of the design; but beyond this, I am satisfied there existsno real necessity for angular position. Both horizontally andvertically, I have often produced equally effective Daguerreotypes. " Ipresume from the last sentence of Mr. Hunt, that he has confined hisexperiments to the smaller sized plates. Hence he may not have thoughtof the effect of the vertical exposure of a large plate. 

In America this is a subject of no little importance. When animpression is to be developed upon a plate fifteen by seventeen inches, were we to use an angle of about 45 deg. , it would be found to make aperceptible difference in the appearance of the image. By examiningthe wood tops of our baths as formerly made, it will be found thatthere is a great variation in the distance from the mercury to thedifferent portions of the plate. By measuring one of these tops forthe size plate above mentioned, I find the distance to the nearestpoint between the mercury and the plate, to be thirteen, and the middlepoint sixteen, and the furthest point twenty-one and a half inches: bythis we see that one point of the plate is eight and a half inchesfurther from the mercury than the nearest point; even this is not thevariation there would necessarily be, were we to adopt the angle of 45deg. As urged by Daguerre. 

Among our principal professors, the bevel top will not be found in usewhere the large plates are used. Should any one feel desirous to testmore minutely the effect produced by a bevel top bath, I would suggestto them to place a frame, so constructed as to hold three sixth sizeplates, and fit it to the top of the bath, and so arrange it withopenings that the plates may be placed, one at the nearest point of themercury, the second midway, and the third to the greatest distance, andby placing the plates over at one and the same time, the experimenterwill be enabled to judge if there exists a difference in thedeveloping. In speaking of the above, reference is had to baths to theordinary heights used by operators. 

We will now proceed to examine the effect produced by mercurial vaporupon the plate at different lengths of exposure. In someinvestigations which I have made upon the appearance of theDaguerreotype impressions when developed over mercury at 90 deg. C. (194 deg. F. ), the following was the result. Plates, coated andexposed to light in our usual manner of operating, produced on exposureof

1/2 minute, whole impression, deep blue. 

1 minute, ashy and flat; no shadows; linen, deep blue. 

1 1/2 minute, coarse and spongy; shadows, muddy; drapery, dirty reddishbrown. 

2 minutes, shallow or watery; shadows, yellowish; drapery, brown. 

2 1/4 minutes, soft; face, scarcely white; shadows, neutral; drapery, fine dark brown linen somewhat blue. 

2 1/2 minutes, clear and pearly; shadows, clear and positive, of apurple tint; drapery, jet black, with the dark shades slightly frostedwith mercury. 

2 3/4 to 3 minutes, hard and chalky; shadows, harsh; drapery, roughened, and misty with excess of mercury. 

The foregoing results will be found general. 

There are numerous opinions among our operators in regard to thequantity of mercury necessary for a bath. As regards this, I need onlysay, similar results occur when two pounds or two ounces are used, butthe quantity generally employed is about a quarter of a pound. I am ofthe opinion that one ounce will answer as well as a larger quantity. Iknow of no better proof in favor of a small quantity than thatpresented in the following incident. Several years since, an operator(Mr. Senter, of Auburn, N. Y. ) of my acquaintance, was requested to goseveral miles to take a Daguerreotype portrait of a deceased person. He packed up his apparatus and proceeded over a rough road for somedistance to the house where he was to take the portrait, and arranginghis apparatus, with all the expedition which the occasion required, after having everything in usual order (as was supposed), he proceededand took some ten or twelve very superior impressions. They were fine, clear, and well developed. After taking the number ordered, heproceeded to repack his apparatus, and to his surprise, when he took upthe bottle he carried the mercury in, he found it still filled, andnone in the bath, except only such particles as had adhered to thesides, after dusting and being jolted for several miles over the roughroad. From this it will be seen that a very little mercury willsuffice to develop fine proofs. I saw some of the impressions referredto above, and they were certainly well developed, and very superiorspecimens of our art. 

Removing the Coating. --After the impression has been developed over themercurial vapor, the next step is to remove the sensitive coating. Forthis purpose the following solution is used:

Put about two ounces of hyposulphite of soda in a pint of water, whichshould always be filtered before using. A convenient way of doing thisis to have two bottles, and a large funnel with a sponge pressed intothe neck of it; or, what is better, some filtering paper folded in it. The solution in one bottle, the funnel is placed in the other, and thepicture held over it; when the solution is poured on the plate, it runsfrom it into the filter, and is always ready for use. 

It is best that the washing be done immediately on the plate comingfrom the mercury bath. If allowed to stand long with the coating on, it assumes a very dark tint--as the operation of the light continues, though less active than while exposed in the camera, and destroys thatbrightness which would otherwise have been obtained. It is preferableto wash and gild a picture without it first being dried; yet when thereare doubts of its giving satisfaction, there would sometimes be asaving by drying and getting the decision of the subject beforegilding, as this last injures the plate for another impression. First, light your spirit-lamp, then with your plyers take the plate by thelower right-hand corner, holding it in such a manner that the plyerswill form in a line with the upper left-hand corner; pour on, slowly, the hyposulphite solution, slightly agitating the plate, until all thecoating is dissolved off; then rinse off with clean water, and if it isnot to be gilded, dry by holding the plate perpendicular with thebottom left-hand corner lowest, and applying the blaze of thespirit-lamp to the back, at the same time blowing gently downward onthe face of the plate. 

The hyposulphite solution should be often filtered through a sponge, and it will answer for a great number of washings. Yet it is observedthat the mercury collects in this solution in small globules; theseoften come in contact with the plate, causing white spots, which spoilthe impression. They should be guarded against, and the solutionrenewed. Again, in order to prevent streaks or scum on the surface ofthe plate, it is necessary that the coating should be removed with agood degree of uniformity. I find in practice that the hyposulphite ofsoda in our market varies much as regards strength, and consequentlythe rule to be adopted is to make a solution of sufficient strength toremove the coating in about ten seconds. I am aware that it may besaid that this strong solution would have a tendency to injure theimpression by destroying in a measure the sharpness of outline. Tomeet this, it need only to be said that the preventive is, to not letthe solution rest on the surface of the plate for a longer time than isabsolutely necessary, and then it should be drenched copiously withwater; hence a chemical action upon the image is prevented and thegeneral operation facilitated. This plan is adopted by our firstoperators with the greatest success. 

If the operator should allow the hyposulphite solution to run over theplate unevenly, it is quite likely that white or blue streaks wouldresult. These it is impossible to remove without injury to theimpression. Some, in order to prevent this, breathe over the surface, thus moistening it and putting it in a condition to receive thesolution with greater uniformity. The plate should be well washed withwater before gilding. 

Gilding, or Fixing the Image. --The next process to be given is that forfixing the image on the plate. This is done by precipitating a thinfilm of gold over the surface and is productive of the most brillianteffect when prepared immediately after the plate has been washed withwater after the application of the hyposulphite solution, and beforethe plate has been allowed to dry. When, however, the plate has beendried and allowed to stand for any time, before gilding, thehyposulphite wash should be applied as at first, in order to destroyany chemical coating that may have been formed on exposure of the plateto the air. For gilding the larger plates, we have a gilding stand soconstructed that the plate can be put on a perfect level. In practice, I prefer holding the plate with nippers, fastened at one corner. Holdthe plate in the same manner as in removing the coating; pour on thegilding, newly filtered, until the surface is wholly covered, and withthe blaze of the spirit lamp, at least three inches high, apply it tothe back of the plate, moving it about, that the surface may be heatedwith as much uniformity as possible. Continuing this operation, thesurface will generally become covered with small yellow bubbles whichsoon disappear, leaving the image clear and distinct. 

It is advisable to make use of a lamp having a sufficiently strongflame to produce the effect in a few minutes. If after a firstheating, it is found that the impression can admit of a greater degreeof intensity, it might be heated anew; but that is seldom necessary, and often by trying to do too, well, the operator, if he persists inheating certain parts of the plate, may find the liquid dry up justabove the flame, and inevitably cause a stain*; or else the blacks arecovered with a film, or even the coating of gold may suddenlyexfoliate, when small particles are detached from the plate. Theimpression is then entirely spoiled, but the plate may be re-polished. 

* This can be remedied, however, if it is immediately washed over withthe same solution that is on the plate, so that the surface shall notbecome cool; continue for a short time to apply the lamp under, andagitate the plate slightly, and it will soon be free from allimperfections and give a fine clear tone. 

It is not unfrequent that the surface assumes a dark, cloudyappearance. This is generally the best sign that the gilding willbring out the impression with the greatest degree of distinctness. Soon, the clouds gradually begin to disappear, and, "like a thing oflife" stands forth the image, clothed with all the brilliancy andclearness that the combined efforts of nature and art can produce. When in the operator's judgment the operation has arrived at thehighest state of perfection, rinse suddenly, with an abundance of cleanwater, and dry as before described. 

When an impression is dark, the gilding process may be longercontinued; but when light, it should be gilded quickly, as lengtheningthe time tends to bleach the impression and make it too white. Thecause of this appears to be, that with a moderate heat the chlorine ismerely set free from the gold, and remaining in the solution, insteadof being driven off, with its powerful bleaching, properties, itimmediately acts upon the shades of the picture. A dark impression canthus, by a low heat, long-continued, be made quite light. To procurethe best effect, then, heat suddenly with a large blaze, and judging itto be at the maximum, cool as suddenly as possible. 

When the hyposulphite of gold is used instead of the chloride, a lessheat should be employed. 

Coloring Daguerreotypes. --Of all the so-called improvements in theDaguerreotype, the coloring is the least worthy of notice. Yet theoperator is often, in fact most generally, called upon to hide anexcellent specimen under paint. I can conceive of nothing more perfectin a Daguerreotype than a finely-developed image, with clearness oflights and shadows, possessing the lively tone resulting from goodgilding. Such pictures, however, are not always had, and then colormay perform the part of hiding the imperfections. We present thefollowing method as given in Willat's Manual:

"Daguerreotype portraits are now commonly met with beautifully colored;but the coloring is a process requiring great care and judgment, andmany good pictures are spoiled in fruitless experiments. Severaldifferent methods of coloring have been proposed. The simplest modeappears to be that of using dry colors prepared in the followingmanner: A little of the color required, very finely ground, is throwninto a glass containing water, in which a few grains of gum arabic havebeen dissolved. After standing a few moments, the mixture may bepassed through bibulous paper, and the residue perfectly dried for use. The principal colors used are Carmine, Chrome Yellow, Burnt Sienna, Ultramarine and White; boxes fitted with sets of colors properlyprepared, may be obtained of the dealers, and include Carmine, White, Lilac, Sky Blue, Pink, Yellow, Flesh color, Orange, Brown, Purple, Light Green, Dark Green and Blue. With a few colors, however, all therest may be made thus: Orange, by Yellow and Red; Purple, with Blueand Red; Green, Blue and Yellow; Brown, with Umber, Carmine and LampBlack; Scarlet, Carmine and Light Red. While it is true that a littlecolor may relieve the dark metallic look of some Daguerreotypes, itmust not be concealed that the covering of the fine delicate outlineand exquisite gradations of tone of a good picture with such a coating, is barbarous and unartistic. 

"The prevaling taste is, however, decidedly for colored proofs, and thefollowing directions will assist the amateur in ministering to thisperverted taste, should he be so inclined. The coloring shouldcommence with the face, and the flesh tint must be stippled on (notrubbed) with a small camel's-hair brush, beginning from the centre ofthe cheek, taking great care not to go over the outline of the face, and also not to have too much color in the brush; the eyes and eyebrowsmust not be touched with color. After the flesh color is applied, takea piece of very soft cotton and pass it very gently backwards andforwards over the face, so as to soften down the color, and then applythe carmine to give the required tint. For men, the darker tintsshould predominate, and for women the warmer. Very light hair may beimproved by a slight tint of brown, or yellow and brown, according tothe color. In coloring the drapery, the same care must be used. Norules can be laid down for all the different colors required, and theamateur had better obtain the assistance or advice of some oneaccustomed to the use of colors. A little white with a dash of blue ora little silver, will improve white linen, lace, etc. The jewelry maybe touched with gold or silver from the shells, moistened withdistilled water, and laid on with a fine-pointed sable-hair brush. 

"Brilliants may be represented by picking the plate with the point of apin or knife. "

MISCELLANEOUS. 

CHAPTER II. 

Coloring Back Grounds--Transparent ditto--Gilding Dissolvent Solutionfor removing Specks--Solarized Impression--To Purify Water--CleaningMercury--Adhesive Paper--Black Stain for Apparatus--Sealing Wax forBottles--Rouge--Rotten Stone--Potassa Solution--HyposulphiteSolution--Substitute for do. --Gilding Solution--Solution for increasingthe Brilliancy of the Daguerreotype--Bleaching Solution;--ColdGilding--Neutralizing Agents--Buff Dryer--Keeping Buffs inorder--Cleaning Buckskins--Reflector for taking Views. 

To Color Back-grounds--To obtain a properly colored back ground is amatter of no little importance to the Daguerreotype operator. I hadnearly exhausted all patience, and tried the skill of painters toobtain a back-ground that would be suitable to my purpose; but all tono avail. At last I adopted the following method, and at a cost ofcoloring of twenty-five cents, can now produce a back-ground far morevaluable than those which had cost five dollars before. 

Take common earth paint, such as is used in painting roofs; mix thiswith water to about the consistency of cream; then to four quarts ofthis mixture add about one pint of glue water (common glue dissolved inwater, also about as thick as cream). This last will cause the paintto adhere to the cloth, to which it is applied with a common white-washbrush. By applying the brush on the coating while it is wet, it may beso blended that not a line can be seen, and a perfectly smooth color ofany shade can be obtained. The shade of color I use is a lightreddish-brown. Tripoli, rotten-stone, or any earthy matter, may beapplied in the same manner. 

Transparent or Invisible Back-ground. --I give this as originallypublished in my System of Photography, 1849:

"Take a large woollen blanket with long nap, the longer and rougher itis the finer will be the effect produced; stretch it on a frame ofsufficient size, and suspend the frame at the centre of the upper endby a string fastened to a nail in the ceiling, from three to five feetback of the sitter. Having arranged this, fasten another string to theside of the frame, and while the operation is going on in the camera, swing the back-ground from right to left, continuing this during thewhole time of sitting, and you have a clear "transparent" back-ground, which throws the image out in bold relief, and renders the surface ofthe plate invisible. If equalled at all it is only by atmosphericback-ground. I consider it to be the best ever known, and think itneeds but to be tried to afford satisfactory proof that it is so. Although used by few before, since the first edition of this work atleast two thirds of the operators have adopted its use; for any one canat once understand the principle and the effect which it produces. "

It may be added that a motion imparted to to any back-ground wheresoftness is desired, produces an excellent effect. 

Gilding Dissolvent. --To one quart of muriatic acid add as much oxide ofiron (common iron rust) as it will dissolve in two days. This may bedone by putting in the oxide in excess. It should be frequently shook, and when wanted for bottling it should be allowed to stand in order tosettle. When this is done the solution may be poured off, and reducedby adding to it an equal quantity of water; then it is ready for use. This constitutes a gilding dissolvent now in our market. 

Solution for Removing Specks. --There is probably no one cause ofcomplaint so general as "what makes those black specks?" There areseveral causes which produce them, and probably the most general aredust, rouge, or a spray of moisture on the plate. It this be the case, there is no solution which can remove them, as they have prevented achemical action with the silver, and their removal would only exposethe surface of the plate which in itself would afford a contrast withthe impression. Another and less dangerous source of these specks isorganic matter contained in the solution employed in dissolving thechemicals, or the water in washing. Much of the hyposulphite of sodain market contains a sulphuret, which, coming in contact with thesilver surface, immediately causes oxidation. Such spots, as well alsoas most all others found on the plate after it has been exposed in thecamera, can be removed by the following, solution: To one ounce ofwater add a piece of cyanide of potassium the size of a pea; filter thesolution and apply by pouring it on the surface of the plate. In allcases the plate should first be wet with water. Apply a gentle heat, and soon the spots disappear, leaving the impression clear and freefrom all organic matter. 

In the absence of cyanide of potassium, a solution of pure hyposulphiteof soda will answer as a fair substitute. 

To Redeem, a Solarized Impression. --The Daguerreotype plate, preparedin the ordinary manner, should be exposed in the camera a sufficienttime to solarize the impression. Then, before it be exposed to thevapor of mercury, expose it for a very brief period to the vapor ofeither chlorine, bromine or iodine. Then expose over mercury, asusual. I have produced singularly interesting results by this process. 

To Purify Water. --Filter the water well, and then add about three dropsof nitric acid to the pint. This can be used as absolutely pure water, but I would recommend the use of distilled water as preferable. 

Cleaning Mercury. --Make a small bag of chamois skin, pour in themercury, and squeeze it through the leather. Repeat this severaltimes, and filter by means of a funnel made of paper, with a very smallaperture, through which it will escape and leave the particles of dust, or other substances, in the paper. A paper with a pinhole through itwill answer as well, and it is less difficult to make. 

Adhesive Paper. --Take gum arabic, four ounces, put it in a wide-mouthedbottle and pour on water about one-third above the gum. Add half ounceof isinglass, or fish glue, and a small piece of loaf sugar. Let alldissolve, and spread over French letter paper, with a brush or piece ofsponge. If once spreading is not enough, perform the same operation asecond time. 

Black Stain for Apparatus. --Dissolve gum shellac in alcohol, or procureshellac varnish at the druggists', stir in lampblack, and apply with asponge or bit of rag. This will adhere to metal, as well as wood, andis used for the inside of camera, tubes, etc. 

Sealing Wax for Bottles. --Melt together six parts rosin and onebeeswax, and add a small quantity of lampblack; or, if red ispreferable, add red lead. Common white wax is best, as most chemicalsact less upon it. 

When bottles containing bromine are to be sealed, it is well to greasethe stopper. This, however, only when the bottle is in frequent use, for if it were to be sent by any conveyance it would be likely to flyout. 

Rouge. --The method employed by Lord Ross is probably unsurpassed in theproduction of rouge. He has given his process as follows:

"I prepare the peroxide of iron by precipitation with water of ammonia, from a pure dilute solution of sulphate of iron; the precipitate iswashed, pressed in a screw press till nearly dry, and exposed to a heatwhich in the dark appears a dull, low red. The only points ofimportance are, that the sulphate of iron should be pure, that thewater of ammonia should be decidedly in excess, and that the heatshould not exceed that I have described. The color will be a brightcrimson inclining to yellow. I have tried both potash and soda, pure, instead of water of ammonia, but after washing with some degree ofcare, a trace of the alkali still remained, and the peroxide was of anochrey color, till overheated, and did not polish properly. "

Care should be observed to apply rouge in a dry state to the surface ofthe plate. 

I would remark, that so far as my experience has gone, I consider goodrouge fully equal to any other polishing, material for the last orfinishing polishing; consequently I shall not take up my space inenumerating any of the great variety that find few advocates. 

Why Rouge is to be preferred. --"Because it burnishes better, andbecause it assists in fixing the layer of gold, rendering it lesssusceptible of being removed in scales when heated too much. "

Rotten Stone. --"Purchase the best ground rotten stone of the druggist, put a few ounces at a time in a wedgewood or porcelain mortar, withplenty of clean rain water. This should have about forty drops ofnitric acid to the quart. Grind well, and after letting the mortarstand two minutes, pour into a third. After remaining undisturbedeight minutes, finally pour off into a fourth to settle. Rinse backthe sediment in the second and third, and grind over with a new batch. Repeat the operation till you have all in the fourth vessel. Let thisstand several hours, and pour off the water very carefully. Set thedeposit in the sun, or by a stove to dry. When perfectly dry, pulverize, and it is ready for use. With a little trouble you willobtain in this way a much better article than can generally be boughtof dealers. For the last washing, alcohol, or a mixture of alcohol andwater, is preferable. "

Potassa Solution. --The use of a solution of potassa in the preparationof the plate was suggested in the early history of the Daguerreotype. It was thought to possess some peculiar property for improving the toneof the impression. It is used for moistening the rotten stone inpolishing the plate, and may be prepared by putting about an ounce anda half of alcohol in a close bottle, and add half a stick of causticpotash. This will soon become of a deep red color. For use, fill yoursmall bottle, having a quill in the cork, with alcohol, and add a fewdrops of the above, or enough to change it to a bright orange orsaffron color. 

A Substitute for the Hyposulphite Solution. --M. DAGUERRE recommends theuse of a solution of salt water for removing the coating off the plate. I found this of some service at one time during my travels. Myhyposulphite bottle got broke and its contents lost, so as only toleave enough for preparing gilding. I resorted to the use of saltsolution, and found it to answer well. Make a saturated solution ofsalt in water. First wash the plate with clear water; then immerse itin the saline solution, when it should be agitated, and the coatingwill soon disappear. Another process with a salt solution of half thestrength of the above is very interesting and effectual. The platehaving been dipped into cold water, is placed in a solution of commonsalt, of moderate strength; it lies without being acted upon at all;but if it be now touched on one corner with a piece of zinc, which hasbeen scraped bright, the yellow coat of iodine moves off like a waveand disappears. It is a very pretty process. The zinc and silverforming together a voltaic pair, with the salt water intervening, oxidation of the zinc takes place, and the silver surface commences toevolve hydrogen gas; while this is in a nascent condition it decomposesthe film of iodide of silver, giving rise to the production ofhydriodic acid, which is very soluble in water, and hence instantlyremoved. 

This process, therefore, differs from that with hyposulphite. Thelatter acts by dissolving the iodide of silver, the former bydecomposing it. It is necessary not to leave the zinc in contact toolong, or it deposits stains, and in large plates the contact should bemade at the four corners successively, to avoid this accident. 

Gilding Solution. --To one pint of pure rain or distilled water addfifteen grains of pure chloride of gold, and to another pint add sixtygrains of hyposulphite of soda. When dissolved, pour the gold solutioninto the hyposulphite by small quantities, shaking well after eachaddition. The soda solution must not be poured into the gold, as thegold would be immediately decomposed, and the solution turn black, andbe unfit for use. 

Some operators add muriate of potash and other substances, but these donot possess any advantage except in cases where it is necessary tobleach the solarized portions of the impression, and when such is thecase, chloride of sodium (common salt) is probably as effective and isthe most convenient. Add about a teaspoonful to two ounces of thegilding. 

Solution, for Increasing the Brilliancy of the Daguerreotype. --Thissolution will have the effect to thoroughly cleanse the surface of thegilded plate and excite a powerful influence on the general characterof the impression. To a solution of three ounces of water, in which isdissolved a quarter of an ounce of cyanide of potassium, add oneteaspoonful of a solution containing six ounces of water and half anounce of each pure carbonate of potash, alum, common salt, gallic acid, sulphate of copper, and purified borax. While the plate is wet, pouron a little, and heat it with a powerful blaze. The effect will bequickly produced, in from three to fifteen seconds. Rinse and dry, asin the gilding. 

Bleaching Solution. --Make a saturated solution of muriate of ammonia(sal ammoniac) in pure water, and filter through paper. Reduce with anequal quantity of water when used. When the linen or any other portionof the impression is badly solarized, after removing the coating, rinsewith water; then pour this upon the surface in the same manner as thegilding solution. If the solarization be very deep, apply the lampbeneath, and warm the plate a trifle. Now pour off, and, withoutrinsing, apply the gilding. The whole operation must be quicklyperformed, or the chlorine soon attacks the shades of the picture. When properly done, however, the solarized parts are restored to aclear, transparent white. 

Electro, or Cold Gilding. --This process I have adopted, and it producesexceedingly beautiful impressions for the stereoscope, adding a greatcharm to the pleasing effect of that instrument. It also possesses apretty and curious effect on views. It is easy of trial, and may beused by dissolving one gramme of chloride of gold in half a litre ofordinary water, and thirty grammes of hyposulphite of soda in anotherhalf litre of similar water; then pour the solution of chloride of goldinto that of soda, by little and little, agitating it exactly as in M. Fizeau's preparation, of which there is but a variation. 

When you wish to use it, pour some into a plate, or any other vessel ofthe same kind, sufficient to cover the proof; then, after having addedto it a drop of ammonia, immerse the plate in it as soon as you take itout of the mercury-box, after having wiped its back and edges, andagitate the mixture quickly from right to left, so as to dissolverapidly the coating of iodide of silver as usual. As soon as the plateappears white, cease all rapid motion, but continue to give it a slightundulating one; for if it were allowed to remain still for only a fewminutes, the proof would be clouded. By little and little, the surfaceof the plate takes a yellow tint, which darkens more and more, approaching to bistre. You stop therefore, at the color you wish; andwhen the proof has been washed and dried, in the manner previouslyexplained, it will be found to be fixed, without any stain, with alimpid surface, and an extraordinary warm tone. If you were to augmentthe proportions of the ammonia or chloride of gold, the operation wouldprogress much quicker, but then the middle of the proof would be alwaysmuch clearer than towards the border. The mixture may be used severaltimes without being renewed. It does not, however, give such abeautiful color to the impression as when it is newly prepared. Bycommunicating to the vessel containing the solution a continual motion, the impression, when once immersed, will be fixed. During that time, and while attending to anything else, watch its color; and at the endof ten minutes or a quarter of an hour, take it out of the bath and dryit. 

Agent for Neutralizing Bromine, Chlorine, and Iodine Vapors. --Aquaammonia, sprinkled about the chemical or coating room, will soonneutralize all the vapor in the atmosphere of either chlorine, bromine, or iodine. No operator should be without, at least, a six-ounce bottlefilled with ammonia. A little of its vapor about the camera-box has adecided and happy effect. Burnt coffee, pulverized, has also theproperty of destroying the vapors of the above chemicals, as alsoalmost any other agent employed about the Daguerreotype room. Itsdeodorizing properties are such that if brought in contact with airfilled with the odor of decomposing meat, it will instantly destroy alldisagreeable smell. It can easily be used in the Daguerreotype room byplacing a little of the raw bean, finely pulverized, on an old plate, and roasting it over the spirit-lamp. 

Buff Dryer. --There are various methods for keeping buffs dry and freefrom dust. Some place a sheet of iron against the wall at an anglesufficient to put a lamp between it and the wall, and then let the buffrest against the top of the sheet. By this method the buff is for itsfull length close to the heated iron, and at the same time exposed tothe heated atmosphere and any dust that may be free. I would recommendsome arrangement by which the buff would be inclosed. I have found thefollowing to answer the purpose well, which is a box of sheet irontwenty inches long, eight wide and five high, with one end left openand the other closed; the cover is made of the same material, with theedges bent over to go on and off. There are several wires runningthrough the centre of the sides, which it is necessary to cover withcloth or paper to absorb all the moisture that may be made by applyingthe heat, and the buffs are put in and taken out at the open end. Inorder that the heat may be as nearly uniform as possible, an iron barone inch wide, eighteen inches long and one half inch thick, is so bentthat the centre is one quarter inch from the bottom of the box, andthat at least two inches of each end come in contact with the bottom;this being riveted on the bottom, and a lamp with a small blaze appliedto the centre of the bar of iron. This will constitute one of the bestand cheapest buff dryers in use. It may be suspended from the wall byplacing wires around it, or it may stand upon legs. Perhaps a moreconvenient plan is to place it under the workbench in a similarposition to a drawer. One precaution is necessary: when first heatingthe dryer, apply but a very gentle heat. This will prevent anaccumulation of moisture, which would otherwise pass off in steam, coming in contact with the buff, thus causing a dampness. Anothercaution: never have the temperature of the air in the heater more thanten degrees above that which surrounds it. 

When wheels are used, they should be encased in a sheet iron or woodcase. All those made for our market are provided in this respect. 

Keeping Buffs in Order. --This is one of the most important objects toarrest the attention of the operator. Every buff is more or lessliable to get out of order by dust falling upon or coming in contactwith the polishing powder employed in cleaning the plate. The edge ofevery plate should be thoroughly wiped and freed from any material thatmay adhere while cleaning. I have adopted the following method, whichproves highly successful:

Rub the buff leather, holding the face down, with the sharp edge of apair of shears or a piece of glass. This brings out any portion of theskin which may have become matted from any moisture, and also takes outany substance imbedded in it, and prevents it from scratching. Then, with a stiff brush, rub the buff well, and it will be found to workwell. This same process employ on wheels and hand buffs every morning, or oftener, as occasion requires. 

Preparing Buffs. --Two of these are necessary. That part of the stickto be covered should be about eighteen or twenty inches long, and threewide, and made crowning on the face from one end to the other, aboutone half inch. Before covering, these are to be padded with two orthree thicknesses of Canton flannel. The buff should not be too hard, but padded with flannel, so that by drawing it over the plate, it maytouch across the surface. The only proper material for buffs isprepared buckskin; and if prepared in a proper manner, this needsnothing but to be tacked upon the stick. There are several varietiesof wheels employed; the one most generally adopted is Lewis' patent, which consists of several varieties of wheels. Any operator can make asuitable wheel on the same plan of a turning lathe. 

To Clean Buckskins. --When the operator is compelled to purchase anunprepared buckskin, the following is a good process for cleaning it:There is always in the buckskin leather that is purchased, more or lessof an oily matter, which is acquired in its preparation, sometimes evenamounting, to a third of its weight. The following is the mode ofridding it of this noxious ingredient: Dissolve, in about six or sevenquarts of filtered water, about five ounces of potash; when dissolved, wash with the solution an ordinary buckskin; when it has been wellstirred in the liquid, the water becomes very soapy, owing to thecombination of the potash with the oily matters contained in the skin. Throw away this solution and use some fresh water without potash andrather tepid; change it several times until it remains quite limpid. Then gently stretch the skin to dry in an airy shaded place. Whenthoroughly dried, rub it well between the hands. It thus becomes verypliant and velvet-like. 

Reflectors for Taking Views. --There have been excellent camerasintroduced for taking views, but the time of exposure, which isincreased in proportion to the focal length, is considered anobjection; consequently many adhere to the old plan of using thespeculum, or rather, substitute a mirror. I now have one which I haveused for several years and find it equal to any article of the kindhave ever tried. One is easily made by a tin man, at a triflingexpense. Procure a piece of best plate looking-glass, two and a halfby five inches for a quarter, or four by eight for a half-sized camera;put a piece of pasteboard of the same size on the back, to protect thesilvering, and stick around the edge in the same manner as in puttingup a picture. Take a sheet of tin for the large size, or a half sheetfor the other; place the glass crosswise in the centre; bend the endsof the tin over the edge of the glass and turn them back so as to forma groove to hold the glass, and still allow it to slide out and in. These ends of the tin must be turned out flaring, that they may notreflect in the glass. 

Have a tin band about an inch wide made to fit close on the end of thecamera tube; place it on, and taking the tin containing the glass, bring it to an angle of forty-five degrees with the tube, extendingnearly the whole length of the glass in front of the lenses; lap theloose ends of the tin on each side of the tin rim, and having yourcamera turned on the side to throw the view lengthwise, arrange theexact angle by examining the image on the ground-glass. When you haveit exactly right, hold it while it is soldered fast to the band. Takeout your glass and stain the tin black, to prevent reflection. 

CHEMICALS. 

CHAPTER III. 

Bromine and its Compounds--Iodine and its Compounds--Chlorine and itscompounds--Cyanide of Potassium--Hyposulphite of Soda--Hyposulphite ofGold--Nitric Acid--Nitro-Muriatic Acid--Hydrochloric Acid--HydrofluoricAcid--Sulphuric Acid--Accelerating Substances--Liquid Sensitives--DrySensitives, etc. , etc. 

BROMINE. 

An article so extensively used in the practice of the Daguerreotypicart as Bromine, is deserving of especial attention, and accordinglyevery person should endeavor to make himself familiar with itsproperties and applications. 

History. --This element was discovered in 1826 by M. Balard, in themother-liquor, or residue of the evaporation of sea-water. It is namedfrom its offensive odor (bromos, bad odor). In nature it is found insea-water combined with alkaline bases, and in the waters of manysaline springs and inland seas. The salt springs of Ohio abound in thecompounds of bromine, and it is found in the waters of the Dead Sea. The only use which has been made of bromine in the arts is in thepractice of photography. It is also used in medicine In a chemicalpoint of view it is very interesting, from its similarity inproperties, and the parallelism of its compounds to chlorine and iodine. 

Dr. D. Alter, of Freeport, Pa. , is the only American manufacturer, andfurnishes all of the "American Bromine. " Yet we understand muchpurporting to be of German manufacture is prepared from that made inFreeport. This is done by individuals in this city, who get well paidfor the deception. 

For the successful application of bromine as an accelerating agent, weare indebted to Mr. John Goddard of London, who at the time wasassociated with Mr. John Johnson, now a resident of this city. 

Preparation. --The mother-liquor containing bromides is treated with acurrent of chlorine gas, which decomposes these salts, setting thebromine free, which at once colors the liquid to a reddish brown color. Ether is added and shaken with the liquid, until all the bromine istaken up by the ether, which acquires a fine red color and separatesfrom the saline liquid. 

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Solution of caustic potash is then added to the ethereal solution, forming bromide of potassium and bromate of potash. This solution isevaporated to dryness, and the salts being collected are heated in aglass retort with sulphuric acid and a little oxide of manganese. Thebromine is distilled, and is condensed in a cooled receiver, into a redliquid. 

Properties. --Bromine somewhat resembles chlorine in its odor, but ismore offensive. At common temperatures it is a very volatile liquid, of a deep red color, and with a specific gravity of 3, being one of theheaviest fluids known. Sulphuric acid floats on its surface, and isused to prevent its escape. At zero it freezes into a brittle solid. A few drops in a large flask will fill the whole vessel when slightlywarmed, with blood red vapors, which have a density of nearly 6. 00, airbeing one. It is a non-conductor of electricity, and suffers no changeof properties from heat, or any other of the imponderable agents. Itdissolves slightly in water, forming a bleaching solution. 

Chloride of Bromine. --This as an accelerating agent is by manyconsidered superior {75} to the other Bromide combinations. It can bereadily prepared by passing a current of chlorine through a vesselcontaining bromine. A mixture of two parts muriatic acid and one ofblack oxide of manganese, should be put into a flask having a bent tubeto conduct the chlorine vapor into the bromine in another vessel. Thislast vessel should also be supplied with a bent tube for conducting thecombined vapors with a third vessel or receiver. On the application ofthe heat from a spirit lamp to the bottom of the flask, a current ofchlorine gas will be disengaged, and pass into the bromine, when itreadily combines, and gives off a vapor, which, when condensed in thethird vessel, forms a volatile yellowish-red liquid. It is best, evenat ordinary temperature, to place the receiver in an ice bath. Formanner of using, see farther on, under head of Accelerators. 

Bromides. --A bromide treated with oil of vitriol, disengageschlorohyadic acid; but vapors of bromine are constantly disengaged, atthe same time imparting a brown color to the gas. If the bromide betreated with a mixture of sulphuric acid, and peroxide of manganese, bromide is only disengaged. A solution of a bromide gives, with ofnitrate {76} silver, a light yellowish white precipitate of bromide ofsilver, which is insoluble in an excess of acid, and readily dissolvesin ammonia. The precipitated bromide is colored by light like thechloride, but is immediately tinged brown, while the chloride assumesat first a violet hue. The bromides, in solution, are readilydecomposed and chloride being set free, colors the liquid brown. 

In the whole range of heliographic chemicals there is probably notanother collection less understood and being so productive ofinteresting investigation as the bromides. 

Bromide of Iodine. --M. De Valicours furnishes us with the best methodfor preparing this mixture:

"Into a bottle of the capacity of about two ounces, pour thirty orforty drops of bromine, the precise quantity not being of importance. Then add, grain by grain, as much iodine as the bromine will dissolvetill quite saturated. This point is ascertained when some grains ofthe iodine remain undissolved. They may remain in the bottle, as theywill not interfere with the success of the preparation. 

"The bromide of iodine thus prepared, from its occupying so small aspace, can very easily be carried, but in this state it is much tooconcentrated to be used. When it is to be employed, pour a smallquantity, say fifteen drops, by means of a dropping-tube, into a bottlecontaining about half an ounce of filtered river water. It will easilybe understood that the bromide of iodine can be used with a greater orless quantity of water without altering the proportion which existsbetween the bromine and iodine. "

This article forms a very good dry accelerator, and is by some personsthought superior to all others, as it works with great uniformity, andis less liable to scum the plate in coating at high temperatures, orwhen the thermometer indicates a heat above 60 deg. 

Bromide of Potassium--Is prepared by mixing bromine and a solution ofpure potass together, and evaporating to dryness; it crystallizes insmall cubes, and dissolves readily in water. This agent is extensivelyemployed in the paper and glass processes. 

Bromide of Lime. This the principal accelerator used in the Americanpractice, and is the best of all dry combinations at present employed. There are many reasons why the dry is advantageous; these are toofamiliar to repeat. 

"The bromide of lime may be produced by allowing bromine vapor to actupon hydrate of lime for some hours. The most convenient method ofdoing this is to place some of the hydrate at the bottom of the flask, and then put some bromine into a glass capsule supported a little abovethe lime. As heat is developed during the combination, it is better toplace the lower part of the flask in water at the temperature of about50 deg. Fah. ; the lime gradually assumes a beautiful scarlet color, and acquires an appearance very similar to that of the red iodide ofmercury. The chloro-iodide of lime may be formed in the same manner;it has a deep brown color. Both these compounds, when the vaporarising from them is not too intense, have an odor analogous to that ofbleaching powder, and quite distinguishable from chlorine, bromine, oriodine alone. "

Farther on, I have given, in connection with accelerators, a process Iadopt, which is far less tedious and equally reliable. 

Bromide of Silver--May be formed by pouring an alkaline bromide into asolution of nitrate of silver, in the shape of a white, slightlyyellowish precipitate, which is insoluble in water and nitric acid, butreadily dissolves in ammonia and the alkaline hyposulphites. Chlorineeasily decomposes bromide of silver, and transforms it into chloride. 

M. Biot has expressed his opinion, that it is not possible to find anysubstance more sensitive to light than the bromide of silver. This istrue to a certain extent, but in combination with deoxidizing agents, other preparations have a decided superiority over the pure bromide ofsilver. 

Bromide of Gold--Is readily prepared by adding a little bromide to thebrown gold of the assayers, and allowing it to remain some time underwater, or assisting its action by a gentle heat. It forms a salt of abright crimson color, but in its general properties is preciselysimilar to the chloride used in gilding. 

Bromide of Magnesia--Is prepared in the same manner as bromide of lime. 

This mixture is particularly adapted for hot climates, and is used inthis country by some few who regard its use as a valuable secret. 

Bromide of Starch. --This preparation is much used, but not alone. Itis combined with lime by putting about one part in measure of starch tofour of lime. It is prepared by adding bromine to finely pulverizedstarch, in the same manner as bromide of lime. (See Accelerators. )

Experiments with Bromine. --Place in a very flaring wine glass a fewdrops (say ten) of bromine, then place a small piece of phosphorusabout one-twentieth of an inch in diameter. Place the latter on theend of a stick from five to ten feet in length. So place it that thephosphorus can be dropped into the glass, and in an instant combustiongiving a loud report will be the result. 

b. Expose a daguerreotype plate to the vapor of bromine, it assumes aleaden-grey color, which, blackens by light very readily. Exposingthis to mercury will not produce any decided action upon the lights. Immerse it in the solution of the muriate of soda, and the partsunacted upon by light becomes a jet black, while the parts on which thelight has acted will be dissolved off, leaving a clean coating ofsilver. This will be a most decided black picture on a white ground. 

c. Expose an impressioned plate, that has been sufficient time in thecamera to become solarized, to the vapors of bromine, and theimpression will be fully developed and exhibit no signs ofsolarization. The exposure over the bromine most be very brief. Chlorine or iodine will produce the same result. The latter ispreferable. 

Again, should the impressioned plate be exposed too long over the vaporof bromine, the impression would be rendered wholly insensitive to themercurial vapor. Hence this method is resorted to for restoring thesensibility of the plate when there is reason to believe that theimpression would not be a desirable one; as, for example, if a likenessof a child be wanted, and it had moved before the plate had beensufficiently long exposed in the camera, the plate may be restored toits original sensitiveness by re-coating over bromine, as above, thussaving the time and labor of re-preparing the plate for the chemicals. 

d. If by accident (we would not advise a trial to any extent of this), you should inhale a quantity of the vapor of bromine, immediatelyinhale the vapor of aqua ammonia, as this neutralizes the dangerouseffect of the bromine vapor. Every operator should be provided with abottle of ammonia, as a little sprinkled about the chemical room soondisinfects it of all iodine or bromine vapor, and also tends tofacilitate the operation in the camera. 

IODINE. 

History of Iodine. --This is one of the simple chemical bodies which wasdiscovered in 1812 by M. Courtois, of Paris, a manufacturer ofsaltpetre, who found it in the mother-water of that salt. Itsproperties were first studied into by M. Gay Lussac. It partakes muchof the nature of chlorine and bromine. Its affinity for othersubstances is so powerful as to prevent it from existing in an isolatedstate. It occurs combined with potassium and sodium in many mineralwaters, such as the brine spring of Ashby-de-la-Zouche, and otherstrongly saline springs. This combination exists sparingly insea-water, abundantly in many species of fucus or sea-weed, and in thekelp made from them. It is an ingredient in the Salt Licks, saline, and brine springs of this country, especially of those in the valley ofthe Mississippi. It is sparingly found in fresh-water plants, as wellalso in coal, and in combination with numerous other bodies. 

Fermented liquors contain iodine; wine, cider, and perry are moreiodureted than the average of fresh waters. Milk is richer in iodinethan wine; independently of the soil, with which it varies, theproportion of iodine in milk is in the inverse ratio of the abundanceof that secretion. Eggs (not the shell) contain much iodine. A fowl'segg weighing 50 gr. Contains more iodine than a quart of cow's milk. Iodine exists in arable land. It is abundant in sulphur, iron, andmanganese ores, and sulphuret of mercury: but rare in gypsum, chalk, calcareous and silicious earths. Any attempt to extract iodineeconomically should be made with the plants of the ferro-ioduretedfresh waters. Most of the bodies regarded by the therapeutists aspectoral and anti-scrofulous are rich in iodine. 

It is probably to the application of this body that we owe thediscovery of the daguerreotype. There is no record of the precise datewhen Daguerre commenced experimenting with iodine, but by the publishedcorrespondence between him and M. Neipce, his partner, it was previousto 1833. There is no doubt, however, that the first successfulapplication was made in 1838, as the discovery was reported to theworld early in January, 1839. 

Preparation. --Iodine is mostly prepared from kelp, or the halfvitrified ashes of seaweed, prepared by the inhabitants of the westernislands, and the northern shores of Scotland and Ireland. It istreated with water, which washes out all the soluble salts, and thefiltered solution is evaporated until nearly all the carbonate of sodaand other saline matters have crystallized out. The remaining liquor, which contains the iodine, is mixed with successive portions ofsulphuric acid in a leaden retort, and after standing some days toallow the sulphureted hydrogen, etc. , to escape, peroxide of manganeseis added, and the whole gently heated. Iodine distills over in apurple vapor, and is condensed in a receiver, or in a series oftwo-necked globes. 

Properties. --Iodine is solid at the ordinary temperature, presentingthe appearance of dark-grey or purple spangles, possessing a highdegree of metallic lustre. It somewhat resembles plumbago, with whichit is sometimes diluted, particularly when it is fine. Operatorsshould endeavor to secure the larger crystals. It melts at 224. 6 deg. , forming a brown or nearly black liquid. It boils at about 356 deg. , and emits a very deep violet colored vapor. It gives off a veryappreciable vapor, sufficient for all purposes of forming the iodide ofsilver on the daguerreotype plate, at a temperature of 45 deg. Or evenlower. Iodine crystallizes readily. Every operator has found upon theside of the jar in his coating-box, perfectly regular crystals, deposited there by sublimation. 

Water dissolves but a small proportion of iodine, requiring 7000 partsof water to dissolve one of iodine, {85} or one grain to the gallon ofwater. Alcohol and ether dissolve it freely, as does a solution ofnitrate or hydrochlorate of ammonia and of iodides. 

The density of solid iodine is 4. 95; that of its vapor 8. 716. Itgreatly resembles chlorine and bromine in its combinations, but itsaffinities are weaker. It does not destroy the majority of organicsubstances, and vegetable colors generally resist its action. Itcombines with several organic substances, imparting to them peculiarcolors. It colors the skin brown, but the stain soon disappears. 

Chloride of Iodine--Is formed by passing chlorine into a bottlecontaining some iodine. This can be readily done by pouring one ounceand a half of muriatic acid upon a quarter of an ounce of powderedblack oxide of manganese, and heat it gradually in a flask, to which isadapted a bent glass tube. This tube must connect with the bottlecontaining the iodine, and the yellowish-green gas disengaged willreadily combine with the iodine, forming a deep red liquid, and theoperation is complete. The use of chloride of iodine will be referredto in connection with the Accelerators. 

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Iodides. --The iodide treated with the oil of vitriol, instantlyproduces a considerable deposit of iodine; and if the mixture beheated, intense violent vapors are disengaged. The reaction is due tothe decomposition of oil of vitriol by iodohydric acid, water andsulphurous acid being formed, and iodine set free. The iodides insolution are decomposed by chlorine, iodine being precipitated, thesmallest quantity of which in solution is instantly detected by itsimparting to starch an intensely blue color. 

Iodide of Potassium. *--This compound is easily made in the followingmanner: Subject to a moderate heat a mixture of 100 parts of iodine, 75of carbonate of potash, 30 of iron filings, and 120 parts of water. This mass must be thoroughly dried and then heated to redness; theresulting reddish powder is to be washed with water, and the solutionobtained filtered, and evaporated to dryness. It is found that 100parts of iodine yield 135 parts of very white, but slightly alkaline, iodide of potassium. 

* I shall present the preparation of only a few iodides, and such asare more intimately connected with the Daguerreotype. 

Experiment. --On projecting dry pulverized iodide of potassium intofused anhydrous phosphoric acid, a violent disengagement of iodinetakes place, attended by a transient ignition; fused hydrate ofphosphoric acid liberates iodine abundantly from iodide of potassium;this reaction is accompanied by the phenomenon of flame and formationof a considerable quantity of hydriodic acid. 

Iodide of Mercury. --For the preparation of iodide of mercury, Dublancrecommends to cover 100 grms. Of mercury with 1 kilogrm. Of alcohol, to add 124 grms. Of iodine gradually in portions of ten grms. , andagitating between each fresh addition, until the alcohol becomescolorless again. After the addition of the last 4 grms. The alcoholremains colored, the whole of the mercury having become converted intoiodide. The resulting preparation is washed with alcohol; it iscrystalline and of a hyacinth color. 

Iodide of Silver. --This compound is formed upon every plate upon whicha Daguerreotype is produced. The vapor of iodine coming in contactwith the silver surface, forms an iodide which is peculiarly sensitiveto light. 

The various colors produced are owing to the thickness of the coating, and the maximum sensibility of the coating, as generally adopted, iswhen it assumes a deep yellow, or slightly tinged with rose color. 

This compound is largely employed in most photographic processes onpaper, and may be easily prepared by the following formula: By addingiodide of potassium to a solution of nitrate of silver, ayellowish-white precipitate of iodide of silver is obtained, which isinsoluble in water, slightly soluble in nitric acid, and soluble in asmall degree in ammonia, which properties seem easily to distinguish itfrom the chloride and bromide of silver. Chlorine decomposes it andsets the iodine free, and chlorohydric acid converts it into achloride. It fuses below a red heat. Although the effect of light onthe iodide is less rapid than on the chloride, the former soonerturning black, assuming a brown tinge; but when in connection withgallic acid and the ferrocyanate of potash, it forms two of the mostsensitive processes on paper. 

Iodide of silver dissolves easily in a solution of iodide of potassium, and the liquid deposits in evaporation crystals of a double iodide. 

Iodide of Gold. --If a solution of potassium be added to a solution ofchloride of gold, a precipitate of iodide of gold takes place, solublein an excess of the precipitate. A little free potash should be addedto combine with any iodide that may chance to be set free by thechloride of gold. 

Iodide of Lime is prepared by adding iodine to hydrate of lime (whichwill be referred to farther on) until the mixture assumes a lightyellow shade, when wanted for combinations with accelerators, or to adark brown when employed for the first coating. This latter mixturehas been sold in our market under the name of "Iodide of Brome. "

Iodide of Bromine. --(See page 76. )

Experiments with Iodine. --Place a plate which has been exposed in thecamera over the vapor of iodine for a very brief period, and it willpresent the appearance of the impression having been solarized. 

b. Upon a Daguerreotype plate, from which an impression has beeneffaced by rubbing or otherwise, the picture may be made to reappear bymerely coating it over with iodine. 

c. Place in a vessel a little water, into which put the smallestpossible quantity of free iodine and add a little starch, and theliquid will instantly assume a blue color. Advantage is taken of thisfact in the laboratory to detect the presence of iodine in liquids. The starch should be dissolved in boiling water and allowed to cool. There are numerous other interesting experiments that can be performedby the aid of iodine, but it is unnecessary here to consume more space. 

CHLORINE. 

History. --The Swedish chemist, Scheele, in 1774, while examining theaction of hydrochloric acid on peroxide of manganese, first noticedthis element. He called it dephlogisticated muriatic acid. It wasafterwards, by the French nomenclaturists, termed oxygenated muriaticacid, conceiving it to be a compound of oxygen and muriatic acid. Thisview of its notice was corrected by Sir H. Davy (in 1809), who gave itthe present name. In 1840-41, this gas vas employed for acceleratingthe operation of light upon the iodized Daguerreotype plate. JohnGoddard, Wolcott & Johnson, Claudet, Draper, Morse and others, wereamong the first made acquainted with its use. Count Rumford, Ritter, Scheele, Seebert and others, experimented with chlorine in regard toits effect when exposed to the action of light in combination withsilver. In 1845, M. Edward Becquerel announced that he had "beensuccessful in obtaining, by the agency of solar radiations, distinctimpressions, of the colors of nature. "

On the 4th of March, 1851, Neipce, St. Victor, a former partner ofDAGUERRE, announced that he had produced "all the colors by using abath of bichloride of copper, and that a similar phenomenon occurs withall salts of copper, mixed with chlorine. "

Preparation. --This is easily accomplished by putting about two parts ofhydrochloric (muriatic) acid on one of powdered black oxide ofmanganese, and heating it gradually in a flask or retort, to which maybe adapted a bent glass tube. A yellowish-green gas is disengaged, which being conducted through the glass tube to the bottom of a bottle, can readily be collected, being much heavier than the air, displaces itcompletely and the bottle is filled (which can be seen by the greencolor); a greased stopper is tightly fitted to it, and another bottlemay be substituted. 

In all experiments with chlorine, care should be taken not to inhalethe gas!

Properties. --Chlorine is a greenish-yellow gas (whence its name, fromchloros, green), with a powerful and suffocating odor, and is whollyirrespirable. Even when much diluted with air, it produces the mostannoying irritation of the throat, with stricture of the chest and asevere cough, which continues for hours, with the discharge of muchthick mucus. The attempt to breathe the undiluted gas would be fatal;yet, in a very small quantity, and dissolved in water, it is used withbenefit by patients suffering under pulmonary consumption. 

Under a pressure of about four atmospheres, it becomes a limpid fluidof a fine yellow color, which does not freeze at zero, and is not aconductor of electricity. It immediately returns to the gaseous statewith effervescence on removing the pressure. 

Water recently boiled will absorb, if cold, about twice its bulk ofchlorine gas, acquiring its color and characteristic properties. Themoist gas, exposed to a cold of 32 deg. , yields beautiful yellowcrystals, which are a definite compound of one equivalent of chlorineand ten of water. If these crystals are hermetically sealed up in aglass tube, they will, on melting, exert such a pressure as to liquefya portion of the gas, which is distinctly seen as a yellow fluid, notmiscible with the water which is present. Chlorine is one of theheaviest of the gases, its density being 2. 47, and 100 cubic inchesweighing 76. 5 grains. 

Chlorine Water. --This combination, which is used in conducting M. Neipce's process, can be readily prepared by conducting the gas into abottle containing distilled water. One part water dissolves two partsof chlorine. 

Chlorides. --The metallic chlorides are nearly all soluble in water;that of silver and protochloride of mercury being the only exceptions. A metallic chloride, treated with oil of vitriol, disengageschlorohydric acid. Heated with a mixture of peroxide of manganese andsulphuric acid, chlorine is given off, which is easily recognized byits odor and other physical properties. 

The chlorides dissolve in water; give with nitrate of silver, a whiteprecipitate, even in highly diluted solutions, becoming violet coloredand finally black when exposed to the light. The rapidity of thechange of color is proportioned to the intensity of the light. It isinsoluble in nitric acid, but readily soluble in ammonia; it fuseswithout decomposition, forming, when cold, a tough, horny mass, and isreduced by hydrogen and by fusion with carbonate of soda, or with resin. 

Chloride of Bromine. (See page 74. )

Chloride of Iodine. (See page 85. )

Chloride of potassium. --or (Muriate of Potassa). --Dissolve half anounce of carbonate of potassa in water, and neutralize with muriaticacid. Upon concentrating the solutions, cubic crystals will beobtained, having a taste similar to common salt. They consist ofpotassium and chloride, and when dissolved in water they may beregarded as muriate of potassa. 

Chloride of Lime. --Mix half an ounce of slacked lime (hydrate of lime)with six ounces of water, and conduct into this milk of lime, withfrequent agitation, as much chlorine gas as will evolve from two ouncesof muriatic acid and half an ounce of black oxide of manganese. Theliquid clarifies by standing; may be regarded as a solution of chlorideof lime, and must be protected from the air and light. It may also bemade without putting in the water with the hydrate of lime, by merelypassing the chlorine into the hydrate of lime. This last is by someused in preparations for accelerating the operation of takingDaguerreotypes, but when used for this purpose it is in smallquantities. 

Chloride of Calcium. --To one part of water add two parts of muriaticacid, and add pieces of common chalk until effervescence ceases; thenfilter through cotton cloth and evaporate it by placing it in allearthen or porcelain dish, over a slow fire, to the consistency of asyrup. When cooling, large prismatic crystals of chloride of calciumare formed. These must be quickly dried by pressing between folds ofblotting paper and kept carefully excluded from the air, as it readilyattracts hydrogen. For most daguerreotype purposes, the syrup may beat once evaporated to dryness. This is frequently placed in the iodinecoating box for the purpose of keeping the atmosphere dry. It is soeasily made that every operator can provide himself with it in a shorttime, and at little expense. 

Chloride of Gold. --Is prepared by dissolving gold in aqua regia, acomposition of one part of nitric to two parts of muriatic acid. Goldfoil is the best for our purposes; coin, however, answers, in mostcases, for the daguerreotype operator, as the alloy, being so slight isnot noticed in the gilding process. When the latter is used, it willfacilitate the operation to beat it out, forming a thin sheet, and thencutting in small strips. Where purity is required, foil is better. The gold is placed in three or four times its own weight of the aboveacids. For this purpose, an evaporating dish is best (a common saucerwill do); a moderate heat may be applied to favor the action. Themixture should be stirred often with a glass rod; care should beobserved not to apply too much heat, for at a temperature of about 300deg. The chlorine would be expelled and leave a metallic precipitate, which would require re-dissolving. Acid may at any time be added ifnecessary to dissolve the gold, but it is advisable to add as littleexcess as possible, as it would require more time to evaporate. Afterall the gold has dissolved, and the liquid assumes a deep red color, the solution should be allowed to cool, being stirred nearly all thetime. This salt is of a reddish-brown color. It is rarely we find inour market good chloride of gold, as common, salt is used for the bulk;and when the bottles are labelled "15 grains, " "20 grains, " nine-tenthsdo not in reality contain exceeding five grains of chloride of gold. The salt is mixed with the above solution when it is cooling, and givesbright yellow crystals, which some of our uninformed operators conceiveto be the best quality. 

Chloride of Silver. --(Oxide of Silver. )--Take any quantity of silvercoin or other silver, roll or hammer it thin; cut in small pieces. This in order to save time. Put the silver in a glass or earthenvessel (Florence flask is best); pour in nitric acid and water, aboutthree parts of the former to one of the latter. The operation ofcutting up the silver may be facilitated by applying a gentle heat. This blue solution consists of oxide of silver and oxide of copper, both combined with nitric acid. Should the operator wish a puresolution of silver, which, however, is not always used, he may obtainit in the following manner:

To separate the two metals contained in the above solution from eachother, put some bright copper coins into the solution and set it asidein a warm place for three or four days, occasionally giving it acircular motion. The separated laminae are pure silver, which is to bedigested with ammonia until it ceases to be colored blue. The silver, after being washed and dried, is again dissolved in nitric acid, andthe liquid, diluted with water, is kept as solution, of silver. 

Either of the above solutions (the one of oxide of silver and copper, and the pure silver solution) may be prepared for use by putting themin a bottle, with a quantity of water, and adding common fine salt, youobtain a white curdy precipitate of chloride of silver. No matter howmuch salt is used, provided enough be added to throw down all thechloride of silver. This solution should be well agitated and thenallowed to stand for a few minutes; thus the white precipitate is inthe bottom of the bottle. When the water has become clear, pour it offwith care, leaving the sediment behind, then add a fresh quantity ofclean water, shake, let settle, and pour off as before. Repeat thesame for several times, and the excess of salt will disappear, leavingthe white precipitate, which may be drained of the water and dried inthe dark, and kept free from light and air. 

CYANIDE OF POTASSIUM. 

Cyanide of Potassium. --This important article is worthy the undividedattention of every Daguerreotypist. I here give Mr. Smee's process forits preparation. This is from that author's work entitled, "ElectroMetallurgy, " American edition:

"The cyanide of potassium, so often alluded to while treating of themetallo-cyanides, may be formed in several ways. It may be obtained byheating to a dull redness the yellow ferrocyanate of potash, in acovered vessel, filtering and rapidly evaporating it. The objection tothis method, however, is that without great care the whole of theferrocyanate is not decomposed, a circumstance which much reduces itsvalue for electro-metallurgy. By boiling, however, the ignited residuewith spirits of wine this difficulty is said to be overcome, as theferrocyanate is absolutely insoluble in that menstruum, while thecyanuret, at that heat, freely dissolves, and is as easily re-depositedon cooling. 

"There is, however, a much better process by which this salt may beformed, viz. By simply transmitting hydrocyanic acid throughpotassium. Although the modes of making this acid are very numerous, there is but one which is likely to be employed on a very large scale, and that is its formation from the yellow ferrocyanate by means ofsulphuric acid. This process is performed as follows: any givenweight of the yellow salt is taken and dissolved in about five timesits weight of water; this is placed in a retort, or some such analogousvessel, to which is then added a quantity of strong sulphuric acid, twice the weight of the salt, and diluted with three or four times itsquantity of water. A pipe is carried from the neck of the retort tothe receiving bottle, which should be kept as cool as possible. 

"For small operations, those invaluable vessels, Florence flasks, answer well: a bent tube being connected at one end to its month, theother passing into the second vessel; heat should be cautiously appliedby means of an Argand lamp, a little vessel of sand being placed underthe flask, which helps the acid to decompose the salt. Prussic acid isthen generated and passes through the tube to the recipient vessel, which is to be charged with liquor potassae. 

"When the potash is saturated, the operation is completed. The Germansrecommend a strong, alcoholic solution of potassa to be used in thesecond vessel, for in this case, the hydrocyanic or prussic acidcombines with the potassa, forming a hydrocyanate of potassa, or, thewater being abstracted, the cyanuret of potassium, which spontaneouslyprecipitates, on the saturation of the fluid, the cyanuret, beinginsoluble in strong alcohol. The ferrocyanate of potash may beconsidered as containing three equivalents of hydrocyanic acid, two ofpotash and one of iron; but, unfortunately, we can only obtain half theacid from the salt, owing to the formation of a compound during itsdecomposition which resists the action of the acid. The decompositionof this salt taking 2 equivalents or 426 grains (to avoid fractions)would afford 3 equivalents or 81 grains of hydrocyanic, or prussicacid, capable of forming 198 grains of cyanuret of potassium, while inthe retort there would remain 384 grains or 3 equivalents of bisulphateof potash, and 1 equivalent or 174 grains of a peculiar compound, saidto contain 3 equivalents of cyanogen, 1 of potassium, and one of iron(Pereira). It is manifest that, but for this later compound, we mightdouble the quantity of hydrocyanic acid from the yellow salt. "

The decomposition just described is the one usually received; but toomuch reliance must not be placed on its accuracy, for the analysis ofthe several compounds is too difficult for the results to be fullyadmitted. The residue left in the retort speedily turns to one of theblues, identical with, or allied to, Prussian blue. This is at best adisagreeable process to conduct, for the hydrocyanic acid formedadheres so strongly to the glass, that, instead of being freely givenoff, bubbles are evolved suddenly with such explosive violence asoccasionally to crack the vessel. This may be remedied as far aspossible by the insertion of plenty of waste pieces of platinum--ifplatinized, so much the better, as that facilitates the escape of thegas. The heat should be applied to every part of the vessel, and theflame should not be allowed to play upon one single part alone. Largecommercial operations are performed in green glass or stone-wareretorts. 

"Now for one word of advice to the tyro: Remember that you are workingwith prussic acid; therefore, never conduct the process in a room, thefumes being quite as poisonous as the solution of the acid itself;moreover, have always a bottle of ammonia or chlorine by your side, that should you have chanced to inhale more than is pleasant, it willbe instantly at hand to counteract any bad effects. It is stated byPereira, that a little sulphuric acid or hydroferrocyanic acid passesto the outer vessel, but probably the amount would be of no consequencefor electro-metallurgy, otherwise, it might be as well to use aWoulfe's apparatus, and discard the salt formed in the first vessel. To the large manufacturer it may be worth considering whether someother metallo-cyanuret, formed in a similar manner to theferrocyanuret, might not be more advantageously employed, because theresidue of the process last described contains a large quantity ofcyanogen which the acid is unable to set free. 

"There are other modes of procuring prussic acid, besides the one whichhas been so tediously described; but these are found to be moreexpensive. The only one which I shall now notice is the process bywhich it is obtained from bicyanide of mercury. The bicyanide ofmercury itself is formed when peroxide of mercury is digested withPrussian blue, the peroxide of mercury abstracting the whole of thecyanogen from the blue, and leaving the oxides of iron at the bottom ofthe vessel. The solution may be evaporated to dryness, and one part ofthe salt dissolved in six of water; one part of muriatic acid, sp. Gr. 1. 15, is then added, and the solution distilled, when the whole of thehydrocyanic acid passes over, and by being conducted into a solution ofpotassa, as in the former process, forms cyanuret of potassium. Thisprocess, though easier than the first described, is rather given as aresource under peculiar circumstances than as one to be adopted by thelarge manufacturer. The expense is the only objection, but in a smallquantity this cannot be a consideration. 

"In giving this very rough outline of the general mode of formingsalts, the minutiae necessary for chemical work have altogether beenavoided, and those parts alone are entered upon which are moreimmediately necessary for the electro metallurgist to know and practicefor himself. This will account for the long description of thecyanuret of potassium, while the preparation of the equally importantand even more used acids, the sulphuric, muriatic, etc. , commonly foundin commerce, are altogether neglected. 

"In using solutions of cyanide of potassium, the workman should notimmerse his arms into them, otherwise it occasionally happens that thesolution produces very troublesome eruptions over the skin. "

HYPOSULPHITE OF SODA. 

Hyposulphite of Soda. --This salt forms one of the important chemicalsfor the Daguerreotype operator. Its application to this art is of aninteresting nature. It is used to dissolve the sensitive salt ofsilver which remains unchanged during the exposure in the camera. Ithas the property of readily dissolving the chloride, bromide and iodideof silver. It should be pure and free from sulphuret of sodium; shouldthis last be present, it will cause brown spots of sulphurated silverupon the Daguerreotype impression. This annoyance is a great source ofcomplaint from many operators, and ever will be, so long as it isprepared by men who have no reputation to lose, and whose eyes areblinded by the "Almighty Dollar. "

A good article may be prepared as follows:

"Mix one pound of finely pulverized carbonate of soda with ten ouncesof flowers of sulphur, and heat the mixture slowly in a porcelain dishtill the sulphur melts. Stir the fused mass, so as to expose all itsparts freely to the atmosphere, whereby it passes from the state of asulphuret, by the absorption of atmospheric oxygen, into that of asulphite, with the phenomenon of very slight incandescence. Dissolvein water, filter the solution, and boil it immediately along withflowers of sulphur. The filtered concentrated saline liquid willafford, on cooling, a large quantity of pure and beautiful crystals ofhyposulphite of soda. "

Hyposulphite of Gold. --This compound salt is by a few consideredpreferable to the chloride of gold, but our experience has induced usto use the latter, believing we are enabled to produce a more brilliantand warm-toned impression with it. When the hyposulphite of gold isused in gilding, it requires less heat and a longer application, asthere is some danger of producing a glossy scum over some parts of thesurface of the plate. I prepare this salt as follows:

Dissolve one part chloride of gold and four parts hyposulphite of sodain equal quantities of distilled water: pour the gold into thehyposulphite solution, in the same manner as in mixing the gildingsolution; let it stand until it becomes limpid; filter and evaporate todryness. Re-dissolve and add a few grains of burnt alum. 

After standing a few hours, filter and evaporate again. If notsufficiently pure, repeat the crystallization until it is so. Forgilding, dissolve in water and use in the same manner as the commongilding solution. 

N. B. --The four following mixtures were employed in Neipce's process inhis earliest experiments:

Aqueous Solution of Bichloride of Mercury. --Eight grains of bichlorideof mercury in 10, 000 grains of distilled water. 

Solution of Cyanide of Mercury. --A flask of distilled water issaturated with cyanide of mercury, and a certain quantity is decanted, which is diluted with an equal quantity of distilled water. 

Acidulated White Oil of Petroleum. --This oil is acidulated by mixingwith it one tenth of pure nitric acid, leaving it for at least 48hours, occasionally agitating the flask. The oil, which is acidulated, and which then powerfully reddens litmus paper, is decanted. It isalso a little colored, but remains very limpid. 

Solution of Chloride of Gold and Platinum. --In order not to multiplythe solutions, take the ordinary chloride of gold, used for fixing theimpressions, and which is composed of 1 gramme of chloride of gold and50 grains of hyposulphate of soda, to a quart of distilled water. 

With respect to chloride of platinum, 4 grains must be dissolved in 3quarts of distilled water; these two solutions are mixed in equalquantities. 

Acids. --I shall not go into the preparations of the various acidsemployed in the Daguerreotype. This would be useless to the operator, as there are few, if any, that it would be advisable to prepare. It isonly necessary for the experimenter to be made acquainted with theirproperties, and this in order to prevent any haphazard experiments, which are too common among operators. Any person who may be desirousto try an experiment, should first study the agents he wishes toemploy. By so doing much time and money will be saved; while thesearcher after new discoveries would rarely become vexed on account ofhis own ignorance, or be obliged to avail himself of the experience ofothers in any department of science. 

Nitric Acid--Exists in combination with the bases, potash, soda, lime, magnesia, in both the mineral and vegetable kingdoms, and is neverfound insoluble. It has the same constituents as common air, but indifferent proportions. The strongest nitric acid contains in everypound, two and a quarter ounces of water. Pure nitric acid iscolorless, with a specific gravity of 1. 5, and boiling at 248 deg.. Itis a most powerful oxidizing agent, and is decomposed with more or lessrapidity, by almost all the metals, to which it yields a portion of itsoxygen. 

The nitric acid of commerce, is generally the article used by theDaguerreotypist. This usually contains some chlorine and sulphuricacid. It is obtained by the distillation of saltpetre with sulphuricacid. It is employed in the Daguerreotype process for dissolvingsilver, preparing chloride or oxide, nitrate of silver, [the formerused in galvanizing, ] and in combination with muriatic acid forpreparing chloride of gold, used in gilding. It is also used by somefor preparing the plate. 

Acidulated Solution. --This solution is used for cleaning the surface ofthe Daguerreotype plate. It has the property of softening the silver, and bringing it to a state in which it is very susceptible of beingeither oxidized or iodized, hence it contributes to increase thesensibility of the plate. The proportions are to one drop of acid addfrom 15 to 20 drops of water, or make the solution about like sharpvinegar to the taste. 

Nitro-Muriatic Acid. --Aqua Regia is a compound menstruum invented bythe alchemists for dissolving gold. It is composed of colorless nitricacid (aqua-fortis) and ordinary muriatic acid; the mixture is yellow, and acquires the power of dissolving gold and platinum. Thesematerials are not properly oxidized; it nearly causes their combinationwith chlorine, which is in the Muriatic acid. 

Hydrochloric Acid (Muriatic Acid). --This acid forms a valuable additionto the chemicals employed by the practical Daguerreotypist. This acidis formed by acting upon common salt (which is chloride of sodium) byconcentrated sulphuric acid. The water of the acid is decomposed, andits hydrogen combines with the chloride of the salt to form muriaticacid, and this unites with the sulphuric acid to form sulphate of soda;60 parts of common salt and 49 parts of concentrated sulphuric acid, afford, by this mutual action, 37 parts of muriatic acid and 72 partsof sulphate of soda. The muriatic acid of commerce has usually ayellowish tinge, but when chemically pure it is colorless. The formeris commonly contaminated with sulphurous acid, sulphuric acid, chlorine, iron, and sometimes with arsenic. 

Muriatic acid, from the fact of the presence of the chlorine, is usedin the Daguerreotype process for dissolving gold, and in combinationwith various accelerators. Its presence can be detected by ammonia. Astrip of paper dipped in this and waved to and fro will emit a thickwhite smoke if the acid vapor be in the atmosphere. The ammonianeutralizes the acid fumes. By reversing the experiment we candetermine whether vapor of ammonia be in the air, and also deprivethese suffocating and dangerous gases of their injurious properties, and remove them from the air. Every Daguerreotype operator should befurnished with, at least, a six ounce bottle of aqua ammonia. Itsoperation is very nearly the same on bromine and iodine vapor. 

Hydrofluoric Acid (Fluorohydric Acid). --This acid is used to form someof the most volatile and sensitive compounds employed in theDaguerreotype. It is one of the most dangerous bodies to experimentwith: it is volatile and corrosive, giving off dense white fumes in theair. It combines with water with great heat. At 32 deg. It condensesinto a colorless fluid, with a density 1. 069. It is obtained fromdecomposition of fluorspar by strong sulphuric acid. It readilydissolves the silica in glass, and consequently cannot be kept in avessel of that material. It is prepared and kept in lead. It isemployed in accelerators on account of its fluorine. 

One small drop on the tongue of a dog causes death. The operator whowishes to use it should pour some of the liquid for which he intends itinto a graduate, or other vessel, and then add the desired quantity ofacid. If by accident any of the spray should fall upon the skin, itshould at once be copiously drenched with water. 

Sulphuric Acid. --There are two sorts of this acid: one is an oily, fuming liquid; this is made in Nordhausen, in Saxony, and is commonlycalled "Nordhausen sulphuric acid, " or oil of vitriol. The other whichis the kind used in connection with the Daguerreotype, is commonsulphuric acid. It is somewhat thinner, and when undiluted is notfuming. This acid may be obtained in a solid and dry state, calledanhydrous sulphuric acid. 

The common sulphuric acid is made by burning sulphur, which formssulphurous acid. To convert this into sulphuric acid and gain moreoxygen, nitric acid, which is rich in that body, is added. It forms alimpid, colorless fluid, of a specific gravity of 1. 8. It boils at 620deg. ; it freezes at 15 deg. It is acrid and caustic, and intenselyacid in all its characters, even when largely diluted. 

Its attraction for basis is such that it separates or expels all otheracids, more or less perfectly, from their combinations. Its affinityfor water is such that it rapidly absorbs it from the atmosphere, andwhen mixed with water much heat is evolved. It acts energetically uponanimal and vegetable substances, and is a poisonous, dangeroussubstance to get on the skin. It is a powerful oxidizing agent; henceits use in the galvanic battery, for which purpose it is mostly used bythe Daguerreotypist. The fumes of this being so much more offensivethan nitric acid, the latter is sometimes used. It is also employed insome of the more sensitive accelerators. 

ACCELERATING SUBSTANCES. 

Remarks on the Accelerating substances Used in the Daguerreotype. --Ihave now arrived at a point in this work, where the eye of theDaguerreotype public will intently search for something new. Thissearch will prove in vain, at least so far as regards those who haveenjoyed and embraced the opportunities for studying the principles ofour art. Every experienced operator has in a degree become familiarwith the mechanical uses of all the agents employed, while I fear butfew understand the properties, and laws governing those properties, which are so indispensable to produce an image impressed upon thesilver surface. 

There are three substances which form the bases for producing aDaguerreotype; silver, iodine and bromine. Each forms a separate bodywhich is indispensable to the operators success as the art is nowpracticed in America. With these three, compounds of great variety areformed. 

The silver surface is first thoroughly cleaned and freed from allorganic matter, then exposed to vapor of iodine, producing an iodide ofsilver. The plate upon which is this salt, is again exposed to thevapor of bromine, forming a bromo-iodide of silver, a salt also. 

As most of the various accelerators are compounds of bromine, witheither chlorine or fluorine combination, they partake somewhat of thenature of these latter, giving results which can be detected by theexperienced operator. Thus muriatic acid is added for its chlorine, which can generally be detected by the impression produced, being of alight, soft, mellow tone, and in most cases presenting a brilliantblack to that colored drapery. Those who wish to experiment withagents for accelerating substances, should first study to wellunderstand their peculiar nature and properties; as well, also, toendeavor to find out what will be the probable changes they undergo incombination as an accelerator. This should be done before making theexperiments. From the foregoing it will be seen that numerouscompounds are formed from the same basis, and, consequently, it wouldbe a waste of time and a useless appropriation to devote more of ourspace than is necessary to give the principal and most reliablecombination. 

In America, the words "Quick" and "Quick Stuff, " are more generallyused for and instead of the more proper names, "Sensitives, " or"Accelerators, " etc. As it has by use become common, I frequently useit in this work. 

Liquid Accelerator, No. 1. --This mixture was used by me in 1849, and isgiven as it appeared in my "System of Photography, " published at theabove date:

Take pure rain or distilled water, one quart, filter through paper intoa ground stopper bottle, and add, for warm weather, one and a halfounce chloride of iodine; or for cold, one ounce; then add one ouncebromine, and shake well. Now with care not to allow the vapor toescape, add drop by drop, thirty drops of aqua ammonia, shaking well ateach drop. Care must be taken not to add more at a time, as it evokestoo much heat. This mixed, in equal proportions with John Roach'squick, forms an excellent chemical combination. For this purpose, takeone and a half ounce of each, to which add ten ounces water, for warmweather, or from six to seven for cold. Pour the whole into a largebox, and it will work from two to four months. I am now using (1849)one charged as above which has been in constant use for three months, and works uniformly well. The above is right for half or full sizeboxes, but half of it would be sufficient for a quarter size box. 

Coat to the first shade of rose over iodine, change to a deep rosy redover quick, and black about one tenth the first. 

I would not now recommend the addition of "John Roach's quick, " as Ibelieve equally good results can be produced without it. This liquidis now used by many, and is very good for taking views. 

Lime Water Quick. --This mixture is more used at present than all theother liquids ever introduced. It produced the most uniform results, giving the fine soft tone so characteristic in pictures produces fromaccelerators containing chlorine. To one quart of lime water (this canbe had of any druggist) add one and a half ounce of pulverized alum. This should be shook at intervals for twenty--four hours; then add oneounce of chloride of iodine and three fourths ounce of bromine. 

Lime Water. --This is easily prepared by putting lime into water, say apiece of quick-lime about the size of an egg into one quart of water. This should be shook occasionally for two or three days and allowed tosettle, when the water can be poured off and used. 

Use. --To one part of quick add six parts of water; coat to a lightyellow over the iodine, to a rose color over the quick, and recoatabout one tenth. The above coating may be increased or diminished, itmatters not, so that there is not too much, and the proper proportionsare preserved. Some add to the above a small quantity of magnesia, sayabout a teaspoonful to the quart of liquid. 

Liquid Accelerator, No. 2. --The following was for a long time used byone of the first houses in the United States, and probably was one ofthe first liquids ever used. It produces a fine-toned picture, but isnot considered as sure as the lime water quick:

Take rain water one quart, add pulverized alum until it is a littlesour to the taste, and a small piece, say one half inch square, ofmagnesia. Filter through paper, and add chloride of iodine one halfounce, bromine sufficient to take it up, which is a little less thanhalf an ounce. 

Charge with one of quick to six of water; coat over iodine to a softyellow, nearly, but not quite, bordering on a rose; over quick to adark purple, or steel, and back one sixth to one tenth. 

Wolcott's American Mixture. --Van Loan Quick. --This mixture was firstformed and used by T. Wolcott & Johnson and gained great celebrity forits productions. I have now a bottle hermetically sealed that containsabout a half ounce of this mixture prepared in 1841 by John Johnson, now a resident of this city, and the former partner of Mr. Wolcott. The preparation of this mixture, as furnished by Mr. Johnson himself, is given as follows:

"One part of bromine, eight parts of nitric acid, sixteen parts ofmuriatic acid, water one hundred parts. This mixture should be allowedto stand for several days; it improves by age. 

"Use. --A few drops say, 6 to 12, of this mixture, should be put intoabout 6 or 8 ounces of water; it will require frequent replenishing bythe addition of a few more drops. The plate should be coated over thedry iodine to a red just bordering on a slate, and then exposed to themixture only sufficiently long to change the color. If this is notdone in less than six seconds it is not strong enough. Re-coat overthe iodine full one fourth as long as first coating. "

This exceedingly volatile compound is difficult to control from itsinstability; it is but little used. The impressions successfullyproduced by this mixture are very brilliant, and possess a pleasingpeculiarity. 

DRY SENSITIVES. 

Hydrate of Lime. --The operation by which water is combined with lime iscalled slaking. Take a piece of quick lime, common lime used inmortar, and immerse it in warm water for about fifteen seconds; thenplace it in an iron or tin vessel. It will soon begin to swell, evolving a great deal of heat and emitting steam, and soon falls into afine powder, hydrate of lime. This should be well stirred and allowedto cool, and then bottled in order to prevent it from giving off thehydrate and recovering the carbonic acid from the atmosphere. The lastis detrimental to its use with bromine, and is one cause of thecomplaint that "it will not take bromine. " The hydrate of lime should, not be dried over a heat, as has been supposed by many, for in thatcase the hydrogen is expelled and it returns to a carbonate. It isadvisable to cool it in a damp place like a ground cellar. Much of thelime in our market will not, except it be quite damp, combine with thebromine. This is owing to impurities. Nothing is equal tooyster-shell lime, which I use altogether. 

Bromide of Lime. --In preparing large quantities of this, we adopt thefollowing method: Fill a four-quart bottle about two-thirds full ofhydrate of lime; pour into this about one or two ounces of bromine;then shake well, add more of the bromine, shake well and let it standfor a few hours, adding sufficient bromine to give it a fine red color. It is better when kept in the large bottles, as it forms a more perfectcombination: in other words it improves by age. 

Use. --Coat over the iodine to a rose red and then over this mixture toa purple or slate; recoat over the first about one fourth as long asfirst coating. 

Gurneys American Compound. --Of this compound there are twocombinations, one for use, when the temperature of the atmosphere isabove 65 or 70 deg. , and the other at a lower temperature. The firstis called No. 1, the second No. 2. 

No. 1 is prepared by placing hydrate of lime in a bottle, say to threequarts of the hydrate of lime, add one ounce of pulverized burnt alum, and as much chloride of lime as can be put on a quarter of a dollar, and from 15 to 30 grains of dry pulverized iodine, or enough to changethe color of the hydrate of lime, to the slightest possible tinge ofyellow. There had better be less than carry the color to a deepershade. The object of using the iodine is to form a compound withbromine that is not so volatile as the bromine itself. No matter howlittle iodine is combined with the bromine, the vapors possess theirrelative proportion; hence, only enough iodine to prevent "flaring, " oras it is often termed a "scum-coating, " is used. The iodine should bethoroughly combined with the lime, which will take about one or twodays. Should add bromine the same as in bromide of lime, until thecompound assumes a light red color. 

No. 2 is prepared in the same manner as No. 1, except the addition ofthe iodine, which is omitted. 

Use. --No. 1. Coat over the iodine to a bright yellow color, then overthe compound, No. 1, to red color, recoat over iodine, about one sixthas long, as the time occupied in first coating. 

No. 2. Coat over iodine same as above, except recoat over the iodineabout one fourth to one half as long as first coating. 

Dry Quick, No. 1. --Bromide of Lime and Starch. --The following compoundforms an excellent accelerator, and is used by many. It is claimed forthis preparation, that it will hold the bromine longer than otherswhere starch is not employed. As regards this claim we do not think itcan be substantiated. Our experience in practice has led us to theconclusion that there is no great difference as respects durability, but there is some little difference as regards the tone of theimpressions produced by its use. 

To one quart of hydrate of lime add one quart of finely pulverizedstarch. To this mixture add bromine, until it assumes a deep yellow orpink color. 

Starch may be added to any of the dry mixtures. 

Use. --Coat over the iodine to a deep yellow, then over this quick to ared color, recoat about one sixth of the time of first coating. 

I will here again remark, that the exact color of the coating is notessentially provided a proper proportion is preserved. 

I have never seen it stated, though it be a fact worthy of note, that aproportionate time for coating over the iodine and accelerator, willnot answer. For example: if a plate exposed to the vapor of iodine beperfectly coated in sixteen seconds, and then exposed to anaccelerator, (not having iodine in its combination) receives itscoating in four seconds, it will be found that a proper proportionatecoating cannot be preserved by adopting, a proportion of time, but onthe contrary, the time will diminish; for exposure over theaccelerator, as in the above example, if it be desired to coat theplate with twice as much iodine as in the above example, the time wouldbe, over iodine thirty-two seconds, and over the accelerator (topossess a proper proportion) from six to seven seconds. Hence it isthat many inexperienced operators, when wishing to vary their usualmanner of coating, fail in producing a favorable result. They coatcalculating a proportion of time when they should not. 

Dry Quick, No. 2. --Bromide of Lime and Magnesia. --To one quart ofhydrate of lime add one quart of magnesia, and mix them well together;add bromine same as in preparing bromide of lime; coat the same as overdry quick No. 1. This combination produces very uniform results, andis worked with much success by beginners. 

Chloro-Bromide of Lime. --To the bromide of lime add chloride of bromineuntil the mixture becomes a pale yellow color, resembling sulphur. Itshould be shook well, and enough of the chloride of bromine added tobring the compound to a deep blood red color. 

Use. --Coat over the iodine to a pink color, and then over the above toa red, or just changing the color. It should be remembered thataccelerators containing chlorine do not admit of a great change ofcolor of coating on the plate. 

Iodide of Starch. --This mixture can be employed for coating over inwarm weather, and prevent the flashing resulting at high temperatures. It may be used the same as the iodide alone. 

To six ounces of finely pulverized starch, add one fourth ounce of dryiodine. 

Use. --Same as the dry iodine alone. 

The same combination may be made with lime, magnesia and othersubstances. 

Concentrated Solution of Iodine for First Coating. --It may appearstrange to some of our old operators that an aqueous solution of iodinecan be used for coating the plate and forming the iodide of silver. Ithas long been a cry among most operators that it is impossible tosucceed when the iodine box contains dampness. Now this is a greatmistake, and we will here state that in all cases where dampnessappears upon a properly prepared Daguerreotype plate, it is the resultof a different temperature of the metal from the air which surroundsit. Mr. Senter, of Auburn, was the first of our operators who used asolution of iodine for coating the plate, and we several years sincesaw his results, which would rival the production of any otheroperator. A concentrated solution of iodine is prepared by puttinginto a common bottle two thimblesful of hyposulphite of soda and arather larger quantity of iodine, so that there may be more thansufficient. Add to it about 40 ounces of common water (heated to 60 or70 degrees), by little and little, moving, the bottle to warm it, forfear of breaking. After shaking it a short time, the water is rapidlyand strongly colored. The solution should be poured into a bottle witha ground stopper, and when cool used for iodizing. 

A solution of sufficient strength can be made by moistening or justcovering the iodine with water. 

Chloride of Iodine as an Accelerator. --This is probably one of the bestaccelerators that can be used for coating the plate for taking views;it works too slow, however, to meet the wants of the operating room, yet its use was formerly, for a long time, adhered to by some of ourbest professors. In producing views with this, we are successful inobtaining well-developed impressions, with a depth of tone and richnessof appearance not to be met with in the productions of any othersubstances. I give its use as furnished me by an old and experiencedoperator, and published in Humphrey's Journal, vol. I. P. 180:

"As the process of using chloride of iodine may be of interest to someof our subscribers, I take pleasure in giving the followingmanipulation. To one ounce of chloride of iodine add two ounces ofwater; place this mixture in a coating-box, the same as quick stuff;coat the plate with dry iodine to a light yellow, or lemon color; thenbring the coating to a deep pink over the chloride. The plate must berecoated over the dry iodine. "

This combination has been very successfully used in one of our mostextensive establishments in this city, and the superiority of thepictures produced by it was considered as an equivalent for theadditional time required to bring out the impressions. 

Chlorine as an Accelerator. --I shall here refer to but a singleexperiment in which I employed chlorine gas for coating the plate. Iwas provided with a retort, the neck of which was fitted to the jar ofmy coating-box, through a hole drilled for its reception. This wasfitted perfectly tight in my coating-box. I placed some pure undilutedbromine water and the agents necessary for producing chlorine gas (insmall quantity) in the retort. The result was that my first experimentproduced an impression completely solarized in all its parts by anexposure of four seconds of time, which would have required an exposureof twenty seconds to produce a perfectly developed impression by theusual process. 

Another trial immediately produced one of the finest toned impressionsI ever saw, perfectly developed in one second of time. 

My next two or three experiments proved total failures. I was unableto produce even a sign of an impression. By accident my retort wasbroken, and not being in a locality convenient to obtain another, myexperiments were necessarily suspended. 

My attention was not called to this subject again for several years, when I noticed an account of some similar experiments by F. A. P. Barnard and Dr. W. H. Harrington, the latter of whom is now of the firmof Dobyns & Harrington, of New Orleans. 

From reading this article, I found my own difficulties explained. Toomuch of the chlorine gas was present in my coating jar. I would liketo see some of our enterprising operators investigate this combination. 

It is a singular fact, that the vapors of bromine and chlorinecombining upon the iodide of silver, produce a more sensitive coatingthan when the two are combined in solution, as in chloride of brominesolution. Those having Humphrey's Journal at hand, can refer to vol. I. P. 142. 

To use Bromine Water or other Accelerators in Hot Weather. --Anexcellent plan for using bromine water is as follows:

Fill a two-ounce bottle quarter full of it, and then fill the bottlewith fine sand, which serves to preserve a low temperature; then placethe bottle in a porous cup, same as used in the battery; fill this alsowith sand, and close the end with plaster of Paris. Place this in acoating-box, and it will be found to act with great uniformity and bequite permanent. 

Bromide of Lime, another accelerator, can be used in the same manner, except it is, only necessary, when a solid sensitive is used, to mix itwith the sand without placing it in a bottle. This method is employedwith great success by a few, who have regarded it as a secret worthkeeping. 

A Combination, requiring the Use of only One Coating-box. --It is oftenwondered by beginners, why some solution requiring only one coatingcannot be employed. This can be done, but the results are not sosatisfactory as when two or more are employed. Such an accelerator maybe produced by adding alcoholic solution of iodine to a solution ofchlorate of potash, until the latter will take up no more of theformer, and to each ounce, by measure of this solution, ten drops of asaturated solution of bromide in water are added. The solution ofchlorate of potash is made by diluting, one part of a saturatedsolution of the salt with ten parts of water. The use of the chlorateis simply as a solvent of iodine. 

Fats as Accelerators. --The use of fats, oils, or greasy substances, hasbeen one of the most emphatic prohibitions about the Daguerreotypeplate. Yet it has been proved that its presence in a small quantityupon the silver surface has the effect of reducing the time of exposurein the camera from two-thirds to three-fourths. An application may bemade as follows: Pour sweet oil, or rub beef or mutton fat, on a commonbuff, which is free from all polishing powders. With this, buff awell-cleaned plate, and it will leave a scum, which should be mostlyremoved by using another buff, which should be clean. Coat the platein the usual manner, and the result will be a great reduction in thetime of exposure in the camera. The impression produced upon a plateso prepared presents, when coming from the vapor of mercury, a grey, scummy appearance, which, on the application of heat in gilding, doesnot improve; hence its use is not generally adopted. 

We have instituted some investigations upon this subject, and in thepresent volume, we shall not refer to it further. Those wishing tolearn more fully the effect of light upon organic substances will findRobert Hunt's "Researches on Light" an invaluable work. 

LIGHT AND OPTICS. 

CHAPTER IV. 

Light--Optics--Solar Spectrum--Decomposition of Light--Light, Heat, andActinism--Blue Paper and Color for the Walls of the OperatingRoom--Proportions of Light, Heat, and Actinism composing aSunbeam--Refraction--Reflection--Lenses--Copying SphericalAberration--Chromatic Aberration. 

It is advisable that persons engaging in the Daguerreotype art shouldhave at least a little knowledge of the general principles of light andoptics. It is not the author's design here to give a full treatise onthese subjects, but he only briefly refers to the matter, giving a fewfacts. 

It has been well observed by an able writer, that it is impossible totrace the path of a sunbeam through our atmosphere without feeling adesire to know its nature, by what power it traverses the immensity ofspace, and the various modifications it undergoes at the surfaces andinterior of terrestrial substances. 

Light is white and colorless, as long as it does not come in contactwith matter. When in apposition with any body, it suffers variabledegrees of decomposition, resulting in color, as by reflection, dispersion, refraction, and unequal absorption. 

To Sir I. Newton the world is indebted for proving the compound natureof a ray of white light emitted from the sun. The object of this workis not to engage in an extended theory upon the subject of light, butto recur only to some points of more particular interest to thephotographic operator. 

The decomposition of a beam of light can be noticed by exposing it to aprism. If, in a dark room, a beam of light be admitted through a smallhole in a shutter, it will form a white round spot upon the place whereit falls. If a triangular prism of glass be placed on the inside ofthe dark room, so that the beam of light falls upon it, it no longerhas the same direction, nor does it form a round spot, but an oblongpainted image of seven colors--red, orange, yellow, green, blue, indigo, and violet. This is called the solar spectrum, and will bereadily understood by reference to the accompanying diagram, Fig. 1. 

{133}

To those who are unacquainted with the theory of light (and for theirbenefit this chapter is given), it may be a matter of wonder how a beamof light can be divided. 

[Illustration: Fig. 1 (amdg_1. Gif)]

This can be understood when I say, that white light is a bundle ofcolored rays united together, and when so incorporated, they arecolorless; but in passing through the prism the bond of union issevered, and the colored rays come out singly and separately, becauseeach ray has a certain amount of refracting (bending) power, peculiarto itself. These rays always hold the same relation to each other, asmay be seen by comparing every spectrum or rainbow; there is never anyconfusion or misplacement. 

There are various other means of decomposing {134} white light besidesthe prism, of which one of the principal and most interesting to theDaguerreotypist is by reflection from colored bodies. If a beam ofwhite light falls upon a white surface, it is reflected without change;but if it falls upon a red surface, only the red ray is reflected: soalso with yellow and other colors. The ray which is reflectedcorresponds with the color of the object. It is this reflecteddecomposed light which prevents the beautifully-colored image we seeupon the ground glass in our cameras. 

[Illustration: Fig. 2 (amdg_2. Gif)]

A sunbeam may be capable of three divisions--LIGHT, HEAT, and ACTINISM;the last causes all the chemical changes, and is the acting power uponsurfaces prepared to receive the photographic image. The accompanyingillustration, Fig. 2, will readily bring to the mind of the reader therelation of these one to another, and their intensities in thedifferent parts of a decomposed sunbeam. 

The various points of the solar spectrum are represented in the orderin which they occur between A, and B, this exhibits the limits of theNewtonian spectrum, corresponding with Fig. 1. Sir John Herschel andSeebeck have shown that there exists, beyond the violet, a faint violetlight, or rather a lavender to b, to which gradually becomes colorless;similarly, red light exists beyond the assigned limits of the red rayto a. The greatest amount of actinic power is shown at E opposite theviolet; hence this color "exerts" the greatest amount of influence inthe formation of the photographic image. 

(Blue paper and blue color have been somewhat extensively used by ourDaguerreotype operators in their operating rooms and skylights, inorder to facilitate the operation in the camera. I fancy, however, that this plan cannot be productive of as much good as thought by some, from the fact, that the light falling upon the subject, and thenreflected into the camera, is, coming through colorless glass, notaffected by such rays as may be reflected from the walls of theoperating room; and even if it were so, I conceive that it would beinjurious, by destroying the harmony of shadows which might otherwiseoccur. ) The greatest amount of white light is at C; the yellow containsless of the chemical power than any other portion of the solarspectrum. It has been found that the most intense heat is at theextreme red, b. 

Artificial lights differ in their color; the white light of burningcharcoal, which is the principal light from candles, oil and gas, contains three rays--red, yellow, and blue. The dazzling light emittedfrom lime intensely heated, known as the Drummond light, gives thecolors of the prism almost as bright as the solar spectrum. 

If we expose a prepared Daguerreotype plate or sensitive paper to thesolar spectrum, it will be observed that the luminous power (theyellow) occupies but a small space compared with the influence of heatand chemical power. R. Hunt, in his Researches on Light, has presentedthe following remarks upon the accompanying illustration:

[Illustration: Fig. 3 (amdg_3. Gif)]

"If the linear measure, or the diameter of a circle which shall includethe luminous rays, is 25, that of the calorific spectrum will be 42. 10, and of the chemical spectrum 55. 10. Such a series of circles may wellbe used to represent a beam from the sun, which may be regarded as anatom of Light, surrounded with an invisible atmosphere of Heat, andanother still more extended, which possesses the remarkable property ofproducing chemical and molecular change. 

A ray of light, in passing obliquely through any medium of uniformdensity, does not change its course; but if it should pass into adenser body, it would turn from a straight line, pursue a less obliquedirection, and in a line nearer to a perpendicular to the surface ofthat body. Water exerts a stronger refracting power than air; and if aray of light fall upon a body of this fluid its course is changed, asmay be seen by reference to Fig. 4. 

[Illustration: Fig. 4 (amdg_4. Gif)]

It is observed that it proceeds in a less oblique direction (towardsthe dotted line), and, on passing on through, leaves the liquid, proceeding in a line parallel to that at which it entered. It shouldbe observed that at the surface of bodies the refractive power isexerted, and that the light proceeds in a straight line until leavingthe body. The refraction is more or less, and in all cases inproportion as the rays fall more or less obliquely on the refractingsurface. It is this law of optics which has given rise to the lensesin our camera tubes, by which means we are enabled to secure awell-delineated representation of any object we choose to picture. 

When a ray of light passes from one medium to another, and through thatinto the first again, if the two refractions be equal, and in oppositedirections, no sensible effect will be produced. 

The reader may readily comprehend the phenomena of refraction, by meansof light passing through lenses of different curves, by reference tothe following diagrams:--

[Illustration: Fig. 5, 6, 7 (amdg_5. Gif)]

Fig 5 represents a double-convex lens, Fig. 6 a double-concave, andFig. 7 a concavo-convex or meniscus. By these it is seen that adouble-convex lens tends to condense the rays of light to a focus, adouble-concave to scatter them, and a concavo-convex combines bothpowers. 

If parallel rays of light fall upon a double-convex lens, D D, Fig. 8, they will be refracted (excepting such as pass directly through thecentre) to a point termed the principal focus. 

[Illustration: Fig. 8a (amdg_8a. Gif)]

The lines A B C represent parallel rays which pass through the lens, DD, and meet at F; this point being the principal focus, its distancefrom the lens is called the focal length. Those rays of light whichare traversing a parallel course, when they enter the lens are broughtto a focus nearer the lens than others. Hence the difficulty theoperator sometimes experiences by not being able to "obtain a focus, "when he wishes to secure a picture of some very distant objects; hedoes not get his ground glass near enough to the lenses. Again, therays from an object near by may be termed diverging rays. This will bebetter comprehended by reference to Fig. 9, where it will be seen thatthe dotted lines, representing parallel rays, meet nearer the lensesthan those from the point A. The closer the object is to the lenses, the greater will be the divergence. This rule is applicable tocopying. Did we wish to copy a 1/6 size Daguerreotype on a 1/16 sizeplate, we should place it in such a position to the lenses at A thatthe focus would be at F, where the image would be represented at aboutthe proper size. Now, if we should wish to copy the 1/6 size picture, and produce another of exactly the same dimensions, we have only tobring it nearer to the lenses, so that the lens D E shall beequi-distant from the picture and the focus, i. E. From A to B. Thereason of this is, that the distance of the picture from the lens, inthe last copy, is less than the other, and the divergence hasincreased, throwing, the focus further from the lens. "

[Illustration: Fig. 9 (amdg_9. Gif)]

These remarks have been introduced here as being important for thosewho may not understand the principles of enlarging or reducing picturesin copying. 

I would remark that the points F and A, in Fig. 9, are termed"conjugate foci. "

If we hold a double-convex lens opposite any object, we find that aninverted image of that object will be formed on a paper held behind it. To illustrate this more clearly, I will refer to the following woodcut:

[Illustration: Fig. 10 (amdg_10. Gif)]

"If A B C is an object placed before a convex lens, L L, every point ofit will send forth rays in all directions; but, for the sake ofsimplicity, suppose only three points to give out rays, one at the top, one at the middle, and one at the bottom; the whole of the rays thenthat proceed from the point A, and fall on the lens L L, will berefracted and form an image somewhere on the line A G E, which is drawndirect through the centre of the lens; consequently the focus E, produced by the convergence of the rays proceding from A, must form animage of A, only in a different relative position; the middle point ofC being in a direct line with the axis of the lens, will have its imageformed on the axis F, and the rays proceeding from the point B willform an image at D; so that by imagining luminous objects to be made upof all infinite number of radiating points and the rays from eachindividual point, although falling on the whole surface of the lens, toconverge again and form a focus or representation of that point fromwhich the rays first emerged, it will be very easy to comprehend howimages are formed, and the cause of those images being reversed. 

"It must also be evident, that in the two triangles A G B and D G E, that E D, the length of the image, must be to A B, the length of theobject, as G D, the distance of the image, is to G B, the distance ofthe object from the lens. 

It will be observed that in the last cut the image produced by the lensis curved. Now, it would be impossible to produce a well-defined imagefrom the centre to the edge upon a plain surface; the outer edges wouldbe misty, indistinct, or crayon-like. The centre of the image might berepresented clear and sharp on the ground glass, yet this would be farfrom the case in regard to the outer portions. This is calledspherical aberration, and to it is due the want of distinctness whichis frequently noticed around the edges of pictures taken in the camera. To secure a camera with a flat, sharp, field, should be the object ofevery operator; and, in a measure, this constitutes the greatdifference in cameras manufactured in this country. 

Spherical aberration is overcome by proper care in the formation of thelens: "It can be shown upon mathematical data that a lens similar tothat given in the following diagram--one surface of which is a sectionof an ellipse, and the other of a circle struck from the furthest ofthe two foci of that ellipse--produces no aberration. 

"At the earliest period of the employment of the camera obscura, adouble-convex lens was used to produce the image; but this form wassoon abandoned, on account of the spherical aberration so caused. Lenses for the photographic camera are now always ground of aconcavo-convex form, or meniscus, which corresponds more nearly to theaccompanying diagram. "

[Illustration: Fig. 11 (amdg_11. Gif)]

Chromatic Aberration is another difficulty that opticians have tocontend with in the manufacturing of lenses. It will be remembered, that in a former page (133) a beam of light is decomposed by passingthrough a glass prism giving seven distinct colors--red, orange, yellow, green, blue, indigo and violet. 

Now, as has been said before, the dissimilar rays having an unequaldegree of refrangibility, it will be impossible to obtain a focus bythe light passing through a double-convex lens without its beingfringed with color. Its effect will be readily understood by referenceto the accompanying cut. 

[Illustration: Fig. 8b (amdg_8b. Gif)]

If L L be a double convex-lens, and R R R parallel rays of white light, composed of the seven colored rays, each having a different index ofrefraction, they cannot be refracted to one and the same point; the redrays, being the least refrangible, will be bent to r, and the violetrays, being the most refrangible, to v: the distance v r constitutesthe chromatic aberration, and the circle, of which the diameter is a l, the place or point of mean refraction, and is called the circle ofleast aberration. If the rays of the sun are refracted by means of alens, and the image received on a screen placed between C and o, so asto cut the cone L a l L, a luminous circle will be formed on the paper, only surrounded by a red border, because it is produced by a section ofthe cone L a l L, of which the external rays L a L l, are red; if thescreen be moved to the other side of o, the luminous circle will bebordered with violet, because it will be a section of the cone M a M l, of which the exterior rays are violet. To avoid the influence ofspherical aberration, and to render the phenomena of coloration moreevident, let an opaque disc be placed over the central portion of thelens, so as to allow the rays only to pass which are at the edge of theglass; a violet image of the sun will then be seen at v, red at r, and, finally, images of all the colors of the spectrum in the intermediatespace; consequently, the general image will not only be confused, butclothed with prismatic colors. "

To overcome the difficulty arising from the chromatic aberration, theoptician has only to employ a combination of lenses of opposite focallength, and cut from glass possessing different refrangible powers, sothat the rays of light passing through the one are strongly refracted, and in the other are bent asunder again, reproducing white light. 

To the photographer one of the most important features, requiring hisparticular attention, is, that he be provided with a good lens. By theremarks given in the preceding pages, he will be enabled, in a measure, to judge of some of the difficulties to which he is occasionallysubjected. We have in this country but two or three individuals whoare giving their attention to the manufacture of lenses, and theirconstruction is such, that they are quite free from the spherical orchromatic aberration. 

CHAPTER V. 

To make Plates for the Daguerreotype--Determining the Time of Exposurein the Camera--Instantaneous Process for ProducingDaguerreotype--Galvanizing the Daguerreotype Plate--SilveringSolution--Daguerreotype without Mercury--Management of Chemicals--Hintsand Cautions--Electrotyping--Crayon Daguerreotypes--IlluminatedDaguerreotypes--Natural Colors in Heliography--MultiplyingDaguerreotypes on one Plate--Deposit in Gilding--Practical Hints on theDaguerreotype. 

TO MAKE PLATES FOR THE DAGUERREOTYPE. 

I do not give the method employed by our regular plate manufacturers;this is not important, as the operator could not possibly profit by itfrom the fact of the great expense of manufacturing. The followingwill be found practical:

Procure a well planished copper plate of the required size, and wellpolish it, first with pumice stone and water, then with snake stone, jewelers' rouge. Plates can be purchased in a high state ofpreparation from the engravers. Having prepared the copper-plate, wellrub it with salt and water, and then with the silvering powder. Nokind answers better than that used by clock-makers to silver theirdial-plates. It is composed of one part of well washed chloride ofsilver, five parts of cream of tartar, and four parts of table salt. This powder must be kept in a dark vessel, and in a dry place. For aplate six inches by five, as much of this composition as can be takenup on a shilling is sufficient. It is to be laid in the centre of thecopper, and the figures being wetted, to be quickly rubbed over everypart of the plate, adding occasionally a little damp salt. The copperbeing covered with the silvering is to be speedily well washed inwater, in which a little soda is dissolved, and as soon as the surfaceis of a fine silvery whiteness, it is to be dried with a very cleanwarm cloth. In this state the plates may be kept for use. The firstprocess is to expose the plate to the heat of a spirit flame, until thesilvered surface becomes of a well-defined golden-yellow color; then, when the plate is cold, take a piece of cotton, dipped in very dilutenitric acid, and rub lightly over it until the white hue is restored, and dry it with very soft clean cloths. A weak solution of thehydriodate of potash, in which a small portion of iodine is dissolved, is now passed over the plate with a wide camel's hair brush. Thesilver is thus converted, over its surface, into an ioduret of silver;and in this state it is exposed to light, which blackens it. When dry, it is to be again polished, either with dilute acid or a solution ofcarbonate of soda, and afterwards with dry cotton, and the smallestpossible portion of prepared chalk: by this means a surface of thehighest polish is produced. The rationale of this process is, in thefirst place, the heat applied dries off any adhering acid, and effectsmore perfect union between the copper and silver, so as to enable it tobear the subsequent processes. The first yellow surface appears to bean oxide of silver with, possibly, a minute quantity of copper incombination, which being removed leaves a surface chemically pure. 

Another Method. --The best and simplest mode with which we areacquainted is to divide an earthenware vessel with a diaphragm: oneside should be filled with a very dilute solution of sulphuric acid, and the other with either a solution of ferroprussiate of potash, ormuriate of soda, saturated with chloride of silver. The copper plate, varnished on one side, is united, by means of a copper wire, with aplate of zinc. The zinc plate being immersed in the acid, and thecopper in the salt, a weak electric current is generated, whichprecipitates the silver in a very uniform manner over the entiresurface. 

Another Method. --A piece of brass or of polished copper, brass ispreferred, is perfectly planished and its surface made perfectly clean. A solution of nitrate of silver, so weak that the silver isprecipitated slowly, and a brownish color, on the brass, is laiduniformly over it, "at least three times, " with a camel's hair pencil. After each application of the nitrate, the plate should be rubbedgently in one direction, with moistened bitartrate of potassa, appliedwith buff. This coat of silver receives a fine polish from peroxide ofiron and buff. Proofs are said to have been taken on it, comparablewith those obtained on French plates. 

M. SOLIEL'S PROCESS FOR DETERMINING THE TIME OF EXPOSURE IN THE CAMERA. 

M. Soliel has proposed the use of the chloride of silver to determinethe time required to produce a good impression on the iodated plate inthe camera. His method is to fix at the bottom of a tube, blackenedwithin, a piece of card, on which chloride of silver, mixed with gum ordextrine, is spread. The tube thus disposed is turned from the side ofthe object of which we wish to take the image, and the time that thechloride of silver takes to become of a greyish slate color will be thetime required for the light of the camera to produce a good effect onthe iodated silver. 

INSTANTANEOUS PROCESS FOR PROCURING DAGUERREOTYPES. 

The following method of producing Daguerreotypes has by some been namedas above. Most experienced operators have been long acquainted withthe effect of the vapor of ammonia upon the chemically coated plate. Iwill here insert Mr. W. H. Hewett's plan of proceeding. Thisgentleman, in referring to it (published in 1845), says:

"This improvement consists in using the vapor of ammonia, as an objectto accelerate the action of light upon the plate. The effect isproduced upon a simple iodized plate, but still more upon a plateprepared in the ordinary way, with both iodine and bromine. By thismeans, the author obtained impressions instantaneously in the sunshine, and in five to ten seconds in a moderate light; and he hopes to be ableto take moving objects. It can be applied by exposing the preparedplate over a surface of water, to which a few drops of ammonia havebeen added (sufficient to make it smell of ammonia); or the vapor canbe introduced into the camera during the action. In fact, the presenceof ammonia, in the operating-room, appears to have a good effect, as italso neutralizes the vapors of iodine and bromine that may be floatingabout, and which are so detrimental to the influences of light upon theplate. "

GALVANIZING THE DAGUERREOTYPE PLATE. 

In consideration of the importance of galvanized plates, I shallendeavor to give as plain and concise a manner of manipulation aspossible. For some time it was a question among the operatorsgenerally, as to the beneficial result of electrotyping, theDaguerreotype plate, but for a few years past our first operators havefound it a fact, that a well electro-silvered surface is the best forproducing a portrait by the Daguerreotype. 

From my own experiments, I have found that a plate, by beinggalvanized, can be rendered more sensitive to the operation of thelight in proportion of one to five, viz. : if a plate as furnished bythe market, be cleaned, polished, coated and exposed in the camera, ifthe required time to freely develop an impression be ten seconds, asimilar plate prepared in like manner and galvanized, will produce anequally well-defined image in eight seconds. In connection with thissubject, there is one fact worthy of notice; a plate with a very heavycoating of pure silver, will not produce an equally developed image, asa plate with a thinner coating, hence the thin coating, providing itentirely covers the surface, is the best, and is the one most to bedesired. The experiment is plain and simple. Let the slate receive aheavy or thick coating by the electrotype, then polish, coat, expose inthe usual manner, and the result will be a flat, ashy, indistinctimpression; when, on the other hand, the thin coating will produce abright, clear and distinct image, with all the details delineated. 

The style of battery best for the purpose has been, and now is, aquestion of dispute among operators; some preferring the Daniellbattery to Smee's. Some claim the superiority of the first from itsuniformity of action; others, of the latter, for its strength. Iconsider either good, and for the inexperienced would prefer theDaniell. This is more simple in its construction, while it hascertainty in action. The more skillful electrotyper would preferSmee's, and this is the one most generally in use. I would remark thatthe plan of galvanizing plates should be followed by every operator, and when once thoroughly tested, no one will abandon it. 

SILVERING SOLUTION. 

To any desired quantity of chloride of silver in water add, little bylittle, cyanide of potassium, shaking well at each addition, until allthe cyanide is dissolved. Continue this operation, and add thecyanide, until all the precipitate is taken up and held in solution. 

This solution is now ready for the plate-cup. Enough water may be addedto cover any sized plate when held perpendicular in the cup. Thestrength of the solution may be kept up by occasionally adding thechloride of silver and cyanide of potassium. There should alway be avery little excess of the cyanide. 

The plate should be well cleaned and buffed, and the solution wellstirred before it is immersed. Care should be observed to keep thesolution clean, and allow no particle of dust to come in contact withthe surface of the plate. The plate is now to be attached to the poleof the battery. 

After remaining a short time, it assumes a blue color; take it out, rinse freely with pure water, then dry with a spirit lamp, and it isready for buffing. Buff and coat in the usual manner. Some operatorsare in the practice of immersing the plate in the solution and buffingtwice. This additional silvering is no improvement wherever there hasbeen a proper first coating. 

Sometimes the operator is troubled with streaks or scum on the plate. This may arise from three causes, all of which experience must teachthe experimenter to avoid; first, too great an excess of cyanide in thesolution; second, a lack of silver; third, the current too strong. Another annoyance arises from the solution being dirty and the dirtcollecting on the surface. When this is the case, the dirt is sure tocome in contact with the surface of the plate as it is plunged into thesolution, and the result is a scum that it is difficult to dispose of. This can be prevented only by frequent filtering. One thing shouldalways be borne in mind in electrotyping Daguerreotype plates--that inorder to secure a perfectly coated surface, the plate should beperfectly cleaned. In this point, many who have tried the electrotypeprocess have failed, attributing their ill success to other than theproper cause. 

DAGUERREOTYPES WITHOUT MERCURY. 

The following process possesses some interest, and is worthy a trialfrom operators. M. Natterer, of Vienna, discovered a process forobtaining proofs on iodized plates with the chloride of sulphur, without the use of mercury. A plate of silver is iodized in the usualmanner, and then placed on the top of a vessel six or eight incheshigh, having at the bottom, in a small cup, a few drops of chloride ofsulphur; it should remain exposed to the action of the vapor until thesombre yellow color is changed to a red, after which it is brought to afocus in the camera, where it is exposed to the light in the camera, for about the time necessary to produce an ordinary daguerreotype. Theplate is then taken out and examined in the camera by the light of acandle. It often occurs that no trace of the image is as yetperceptible, but if the plate is heated by placing over a spirit lampthe unprepared side, or if left for some time in the dark, or, lastly, if exposed only a few seconds to a weak, dimmed light, the positivepicture then appears with all its shades. Of these three modes ofbringing out the image, the second is superior to the others. 

MANAGEMENT OF CHEMICALS. 

It is necessary, first of all, to know that you have a chemical whichis capable of producing good results when in skillful hands. For thisreason it is best to prepare your own quick, after some formula whichis known to be good. Those quick-stuffs which contain chloride ofiodine are noted for their depth of tone while they probably operatewith less uniformity than those which are destitute of it. Foroperating under ordinary circumstances, especially with an inferiorlight, probably no accelerator is more quick and sure than Wolcott's. It also produces a very fine, white pleasing picture, though lackingthat depth of impression so much to be desired. The dry quick operateswith surety, and its use is simple and easy, producing an impressionmuch like Wolcott's. For those having a good and permanent light, however, we would recommend a chemical giving more body to theimpression. 

There is a class of accelerators called sensitives, claiming to work infrom three to ten seconds, which, however, will be found very little, if any, more sensitive than this. We frequently work it with theordinary coating in twelve and fifteen seconds. The manner in whichthe sensitives are worked is by coating very light. In this way, aflat, shallow picture is obtained in a few seconds; and the same can bedone with any of the more volatile quicks. 

It is a fact not generally known, that a plate coated in a lightchemical room is more sensitive than when coated in darkness. Byadmitting a free, uniform light, and exposing the plate to it a fewseconds after coating, then timing short in the camera, a very light, clear impression is obtained. The time in the camera is reduced inproportion to the previous action of light. The shades, of course, aredestroyed, and the tone injured; still, for taking children, we havesucceeded better by this method than by the use of "sensitives. " Thediscovery of this principle was accidental, while operating where thedirect ray s of the sun, entering the window just before sunset, fellon the curtain of our dark room, rendering it very light within. 

The selection of iodine is not unimportant. Reject, at once, thatwhich has anything like a dull, black, greasy appearance; and selectthat which is in beautiful large crystalline scales, of a purple color, and brilliant steel lustre. 

Solarization, and general blueness of all the light parts of thepicture, were formerly great obstacles to success, though now scarcelythought of by first-class artists. Beginners in the art, however, arestill apt to meet with this difficulty. It is occasioned by dampnessin the iodine box, which causes the plate to become coated with ahydro-iodide of silver, instead of the iodide. The remedy is in dryingyour iodine. If in summer, you can open your box and set it insunshine a few minutes; or if in winter, set it under a stove a shorttime. The true method, however, is to dry it by means of the chlorideof calcium. It has such a remarkable affinity for water, that a smallfragment placed in the open air, even in the dryest weather, soonbecomes dissolved. 

Take one or two ounces of this chemical, heat it in the drying bath, orin a hot stove, to perfect dryness; place it in a small glass toy dish, or large watch crystal, and set it in the centre of your iodine box. Take this out and heat to dryness every morning. Adopt this process, and with your mercury at a high temperature, you will never be troubledwith blue pictures. 

Young operators are apt to impute all want of success in operating totheir chemicals, even though the cause is quite as likely to beelsewhere. Failure is quite likely to occur from dampness in thebuffs, or in the polish; it is therefore necessary to be constantly onthe guard in this quarter. With a view to this, always scrape yourbuffs with a dull knife, or with one blade of your shears, the firstthing in the morning, and after brushing them thoroughly, dry them, either in the sun, by a stove, or in the buff-dryer. It is equallyimportant that the polish and the brush should be kept dry. 

Want of success may arise from vapors of iodine or bromine in thecamera box, mercury bath, or even in the buffs. It is incredible howsmall a quantity of these vapors will affect the effect of light whencoming in contact with the plate, after or during the exposure in thecamera. It is therefore necessary to be cautious not to mix chemicals, nor open your boxes or bottles in your room, but take them out to doit. Never hurry the operation through from lack of confidence in theresult. The fact of anything being out of order, forms no excuse forslighting the process. If unsuccessful, do not pursue the same courseevery trial, but vary with a view to detect the cause of the difficulty. 

In case of a long series of failures, institute a regular course ofinvestigation, after this manner, commencing where the trouble is mostlikely to occur:

1. Are the plates well cleaned?

2. Is the iodine dry? If the impressions come out blue, you may restassured it is not. Take out the iodine, wipe and dry the box, and drythe calcium. 

3. Is the quick battery of the right strength? If dry, it must changethe plate in from six to fifteen seconds. If any of the chloride ofiodine class, it may vary from five seconds to a minute. Begin bycoating light, and increase on each trial, observing the effect. Ifthe light side of the picture seems loth to come out, and shows nocontrast with the dark side, it is to be inferred that your battery istoo strong, and must be reduced with water or set out in the open airfor a few minutes, with the lid off. If working an old battery, neverrenew very strong, or it will work dark and heavy. A battery, to workwell, should be gradually losing strength, but never gaining. An oldbattery, however, may be quickened up and made to work well for sometime, by adding five of six drops of sulphuric acid, repeating thequantity as often as necessary, providing always that acid be not usedin manufacturing the quick. 

4. Have the plates lost their sensitiveness by being many timesexposed to mercury? Clean and burn them; but if French plates, burnlight, or you spoil them. 

5. Are the buff s dry and clean? Examine the plate critically afterbuffing to detect any appearance of scum or film on the surface. Ifso, the longer you buff the more it shows. Scrape and dry the buffsthoroughly. 

6. Is the mercury free from scum and dirt? If not, filter. Is italso far enough from the coating boxes? Should be at least three feet, and kept covered. 

7. Is the mercury sufficiently heated? This is important. Longexposure, however, will answer the same purpose. 

8. Are your lenses clean, and in proper place?

9. Are the tablets in focus with the ground-glass? If you canattribute the failure to none of these, mix a new box of some otherkind of quick, say the dry, for instance. If you fail in the samemanner here, take time, wash your buffs, overhaul all the chemicals, and start anew. Do not be discouraged. 

There is no day so dark but that the sun will shine again. We willclose with this brief summary of advice:

Clean your plates. Keep everything dry. Keep the mercury hot. Followthese instructions carefully, and you must succeed. 

HINTS AND CAUTIONS. 

First of all, cleanliness should be observed. When there is dust ordirt about your room, particularly about the work-bench, failures willbe frequent; for the smallest particles of rotten-stone, when allowedto come in contact with the buffs, will produce scratches on thesurface of the plate, which very much injures the operation, and oftencauses failures. 

Dust flying about the room is injurious, if allowed to fall on theplate, either before or after it has been coated, as it causes blackspots which cannot be removed. 

The polished plate should not be allowed to come in contact with astrong current of air, for it tends to oxidize the surface. Breathingon the surface should also be avoided, for the same reason. 

The plate should, in all cases, be buffed immediately before using, andnot allowed to stand any length of time. It should be held with thepolished face downward. 

It is always best that the plate should be of the same temperature ofthe atmosphere in the room. 

Keep the camera and mercury-bath perfectly free from the vapors ofiodine and bromine; for the presence of the slightest degree of eitherof the above will injure the impression in no small degree. As apreventive, let the camera be exposed to the sun or fire for a fewminutes in the morning. 

Filter your mercury often, to keep the surface free from film and dust. 

The hyposulphite solution should be filtered through sponge every timeit is used. 

The direct rays of light must not enter the camera in conjunction withthose reflected from the object; or the picture will be veiled, and thecolor of the plate changed to a thick green. 

If the plate be iodized only to a light-yellow, the result might be ofa bluish or grey tinge: and this is generally the case, when the quickis new and strong, and there is an excess of it on the plate, and yetnot enough to form the bromide iodide of silver; in which case it wouldwholly spoil the impression. 

Your iodine will be found to operate more successfully, when the timerequired for coating the plate does not fall short of fifteen seconds, or exceed one minute. 

Too quick coating can be avoided by using less iodine in your box. Inthe summer months, when the weather is 80 deg. And over, one quarter ofan ounce, or even less, will work to advantage. 

ELECTROTYPING. 

I am indebted to Mr. J. H. Fitzgibbons for the following process, whichhe employed in producing the excellent specimens he exhibited at theCrystal Palace:

"I shall endeavor to lay down in as comprehensive a manner as possiblethe method by which I have been enabled to produce the mostsatisfactory results. I use a Smee's battery (another kind will do). After filling the cell, of common size, nearly full with water; addabout quarter of an ounce of sulphuric acid. Mix this well, and let itstand for about three hours, or until the action of the battery becomesweak, when it is in order to work with a very uniform action. Put onepound of sulphate of copper in one quart of water; stir it until thesulphate of copper is all dissolved, and then add one half ounce ofsulphuric acid and a quarter of an ounce of nitric acid. Thissolution, well mixed, should be filtered, and it is ready for use. Itis very important that the solution should be kept clean, clear, andfree from all foreign substance. The above quantity of this solutionwill be found sufficient for electrotyping a dozen of the sixth-sizeplates. When it is required to be strengthened, it is only necessaryto add a little of the sulphate of copper. 

"With the battery prepared as above, and the solution of sulphate ofcopper in a vessel of proper dimensions to receive your plate, connectthe galvanic current, and immerse the impressioned plate, letting itremain until a thin film of copper has been formed, then the batterycan be strengthened, and the impression will be of sufficient thicknessto be removed in from eight to twelve hours. An old Daguerreotypeplate attached to the opposite pole of the battery (copper side towardsthe face of the plate to be electrotyped), will answer the same purposeas the silver-plate. 

"The great difficulty in taking an electrotype impression, andpreserving the original, has been attributed to the battery being toopowerful. I am led to believe from practice that the principaldifficulty has been in the Daguerreotype plate itself, for if we use animpression that has been taken but a few days, and taken in the usualway, we will find it difficult to succeed without spoiling both thecopy and original, and so also with an old impression. 

"I have found the most certain method to be as follows:--Coat theDaguerreotype plate as usual, except use less of the accelerators, theproportion of iodine coating being greater, of course the time ofexposure in the camera will be lengthened. Mercurialize it at about atemperature requiring to develop the image, from six to eight minutes, at least. Gilding the Daguerreotype has much to do towards producing agood electrotype copy. This should be done by applying a little heat, and gilding very slowly, giving a coating of gold with the greatestpossible uniformity. By this method, I have been enabled to produceany number of proofs. I have produced a dozen from one impression, andit remains as perfect as when first taken. 

"By a little judgment and care the operator will be enabled to producethe electrotype copy of the Daguerreotype plate without any difficulty. The electrotype copy should be immediately put under a glass and sealedin the same manner as the ordinary Daguerreotype. "

CRAYON DAGUERREOTYPES. 

This process is patented in the United States, by J. A. Whipple, ofBoston, and of course no honorable person will use it for his ownbenefit without purchasing a right. 

A white back-ground is generally employed, the object being to blur thelower portion of the plate, leaving the head of the subject in relief. Every Daguerreotypist is familiar with the fact that a motion of anybody between the camera and the sitter will cause a "blur. " Cut a pieceof thin paper and scallop it, making a semicircle. This is keptstraight by means of a wire frame, and it is to be moved in front ofthe lower part of the body of the sitter during the time of exposure ofthe plate in the camera. Develop over mercury as usual, and the resultwill be a crayon Daguerreotype. 

Another method is to have a wheel with a hole cut through it of adiameter of about 12 inches. This hole is so cut as to leave teethresembling those of a large saw. This wheel is so arranged that it canbe turned around, which should be done during the time of exposure inthe camera. It must be placed between the camera and the sitter, andat such a distance from the camera as to allow such proportion of thebody of the sitter be seen upon the ground-glass as is desired. Itwill be readily seen that by turning this wheel during the operationwill produce the same result as the paper being moved in the othermethod. The teeth make the "blur. " The side of the wheel towards thecamera may be black, by which means the result will be a dark insteadof a light border. 

ILLUMINATED DAGUERREOTYPES. 

This process is also patented, and the remarks on the preceding subjectwill apply in this case. The plate is prepared and exposed as in theusual method of the Daguerreotype. A white back-ground is employed. Let the head of the sitter come in the middle of the plate, and beforeexposing it to the vapors of mercury, put a small mat or diaphragm, having a small hole through it, over or directly on the surface of theplate. This diaphragm should be bevelled, and the bevel should betowards the surface of the plate; this, in order to prevent too sharp aline on the impression. It will be readily seen that if animpressioned plate so covered is placed over the mercury, it will bedeveloped on such portions only as are exposed. The principle is sofamiliar that further explanations are unnecessary. 

NATURAL COLORS IN HELIOGRAPHY. 

This subject is worthy the attention of every operator. The followingprocess is so plain and easy of trial that any Daguerreotypist can tryit. This is as given by Mr. James Campbell, and was published inHumphrey's Journal of the Daguerreotype and Photographic Arts, vol. 5, page 11. Mr. Campbell has done much to further the process announcedby M. Neipce, and his experiments have proved highly successful. 

The following is submitted as worthy of trial:

"The proper preparation of the chloridated plate, to enable it toreceive colored impressions is an object of the first importance tothose wishing to experiment on it, and consequently requires particularnotice. The plate may be prepared by making it the positive pole of abattery, and letting it at the same time be immersed in chlorine water. The negative pole should be a slip of platinum. All the colors may beproduced from a plate so prepared if the chlorine and water are in theright proportions; but generally one color or the other predominates, according to the amount of chlorine in the liquid. By adding thechlorides of strontian, uranium, potassium, sodium, iron, or copper tothe liquid, various effects may be produced, and these bodies will befound to produce the same color on the plate that their flame gives toalcohol. 

"The honor of this discovery is due to M. Neipce. Copper gives avariegated flame; hence many colors may be impressed on a plateprepared with a solution of its chloride. 

"M. Neipce recommends a solution of the mixed chlorides of copper andiron, and it is with these, that I have been most successful. As thechlorides of copper and iron are not much used in the arts, they arenot generally found for sale in the shops; and it may be well tofurnish those not much versed in chemistry with an easy method ofpreparing them. 

"They may be made directly from either metal by dissolving it inhydrochloric acid; but they may be formed by a cheaper method, and bywhich also the acid fumes are avoided. 

"Sulphate of iron or copper, or both together, may be dissolved inwater and then neutralized with common crude potash, or its carbonateor bicarbonate--known commonly as pearl ash and saleratus. If eitherof the latter be used, there will be formed sulphate of potash and acarbonate of the metal used, and there will also be a considerableeffervescence of carbonic acid, which will, if care is not taken, causethe mixture to run over the vessel. After the copper or iron salt isneutralized, which is known by its ceasing to effervesce, the carbonateof the metal will settle slowly, and will at first nearly fill thevessel. The supernatant fluid, which is sulphate of potash insolution, may now be carefully poured off, and its place filled withwater; this operation should be repeated several times until the waterwhich passes off is tasteless. The carbonate of the metal rapidlychanges to an oxide by contact with the air, and it will generally befound, when it is sufficiently washed, that it is at least half oxide. On adding hydrochloric acid cautiously to the mixture, a chloric of themetal will be formed, and carbonic acid will be evolved from theremaining carbonate. The chloride formed is soluble; but as there aretwo chlorides of these metals, and we wish to produce the one whichcontains the most chlorine, it is best to add the acid cautiously untilthe solution is decidedly acid. After filtering the solution, it isfit for use; and it should be preserved in well-stoppered bottles. Thewater used should be rain or distilled water. 

"About one part of the mixed chlorides should be used to three or fourof water. 

"The battery may be either Smee's, Daniell's, or Grove's; if of eitherof the former, it should be of two series; if of the latter, one cup issufficient. 

"The plate on being immersed in the liquid, almost instantly takes aviolet color. It should be allowed to remain from two to five minutes, according to the strength of the battery, and until it becomes nearlyblack. It should now be carefully washed, and afterwards heated over aspirit lamp until it takes a cherry-red color, and it is then ready forexposure in the camera. Before speaking of exposing the plate, it maybe well to speak of some difficulties which the inexperienced operatormay find in preparing it. If the battery is not in good order, and asufficient current is not passed through the solution, the plate willbecome coated--and apparently almost as well as when the battery isworking well--but on exposure it will give a negative picture, and butlittle colored; while if the battery is in good order, the impressionis invariably positive. 

"Sometimes on heating the plate after washing, the surface is coveredwith spots or assumes a variegated appearance. This indicates that thesolution is impure, or that the plate have not been thoroughly washedand are still contaminated with the soluble chlorides which arecontained in the solution. 

"From the fact that the plate if prepared with positive electricitygives a positive picture, while it prepared otherwise it gives anegative, it is evident that electricity plays an important part inthis process. The same is true to some extent with the compoundsformed with iodine, bromine, and fluorine. 

"On heating the plate, the brown coating of chloride melts into atranslucent enamel, and the heat should be withdrawn when a cherry-redcolor is produced. It the heat is continued longer, the plate assumesa lighter color, and becomes less sensitive; and the enamel willfinally scale off. To produce a picture by the ordinary process of M. Neipce, unaccelerated, it should be exposed for from three to fivehours to sunlight in the camera, though pictures may be procured bycontact, in from fifteen to thirty minutes. "

MULTIPLYING DAGUERREOTYPES ON ONE PLATE. 

I have produced some interesting specimens of the Daguerreotypic art, by exposing in the camera only a portion of the sensitive plate to theaction of light. When on the exposed portion an image is formed, thentaking the tablet into the dark room, change ends and expose thesensitive portion, and produce another image, developing as usual. This plan is adapted for taking likenesses for lockets. Two images canbe presented as sitting side by side, by covering half the plate withblack paper, and exposing as before. In this manner we have beenenabled to surprise persons by exhibiting their portrait on the sameplate with a stranger's. Daguerreotypists must be cautious inpracticing this, as it might not be agreeable to the parties whoselikenesses are together, by the above process. It is impossible toproduce an impression without a line being seen where the edge of thepaper prevented the operation of the light. 

I have recently seen a fine specimen produced by another plan, whichfar exceeds the above, there being no line, or any peculiarity denotingtwo exposures. The specimen referred to, was a gentleman representedon one plate by two full length portraits. This was produced by usinga black velvet for the background. The plate was exposed sufficienttime to produce one impression, and then the gentleman assumed anotherposition, and is repeated as looking at himself. From the fact thatthe time required to develop black velvet being so much longer thanthat for producing a portrait, we are enabled to produce the aboveinteresting results. 

DEPOSIT IN GILDING. 

Regarding specks from bad water, I would remark that gilding should bemade only with distilled water. Thus made, it produces very littledeposit, even by long keeping. It therefore preserves its originalstrength, and works with great uniformity. 

Every grain of deposit contains at least 7-10 its weight of gold, easily discoverable by the blowpipe. Such gilding is continuallydeteriorating, which with good chloride and distilled water may beprevented. Distilled water should also be used for the hyposulphite. And for cleaning plates. Any good, clear water may be afterwards usedfor washing off, with equally good results. I am very rarely troubledwith specs, and deem this as the main reason. 

With a portable still attached to a cooking stove, I obtain half agallon of water per hour, and with very little trouble. A small tinretort or still connected with a Leibig's condenser, would not add muchto the "traps" of the travelling operator, and save him many adisreputable specimen. --T. J. BAILEY. --Humphrey's Journal. 

PRACTICAL HINTS ON THE DAGUERREOTYPE. 

The following is from Humphrey's Journal, vol. 5, and from the pen ofDr. WM. HARRINGTON, one of the most able writers upon the subject ofthe Daguerreotype in this country:

THE CAUSE OF THE DIFFICULTY THAT SOMETIMES OCCURS TO PREVENT THEPRODUCTION OF A CLEAR IMPRESSION UPON A DAGUERREOTYPE PLATE. 

Beyond all doubt this is traceable to dampness. Truly this is not anew thought; but where does this dampness come from? How does itoriginate, and where is it located? Generally it has been referred toa point entirely remote from its real location. 

This dampness exists particularly upon the surface of the plate; isobviously derived immediately from the atmosphere; and is owing to acertain relative temperature of the plate with the hygrometriccondition of the atmosphere. 

Whenever this relation exists between the plate and atmosphere, aprecipitation of moisture takes place upon the surface of the plate, which render all efforts at polishing impracticable. This interferenceis not confined to the buffing operation alone, but sometimes isdiscoverable even in the ordinary process of scouring. Every one atall experienced in this art will remember that it is not always an easymatter for him, by scouring, to bring his plate to the desired lustre. All his efforts become unavailing; the more he rubs, the duller thesurface of his plate appears; and although he renews his cottonrepeatedly, still he is obliged to content himself with anunsatisfactory finish. 

This relative condition is not confined to any particular season of theyear, nor to any certain thermometric temperature; but may occur insummer as well as in winter; the weather being warm or cold, wet ordry, clear or cloudy, raining or shining. Under any of thesecircumstances, if the relation of the plate and atmosphere be such asto invite upon the plate a precipitation of humidity from theatmosphere, the prospect of producing a clear impression is quiteproblematical. 

It is reasonable to expect this occurrence from the fact that metal isa good radiator, and radiation reduces the temperature of a metallicbody below that of the atmosphere. Consequently, if this relativecondition happens, the result will be as I have stated. 

Bodies may be colder than the atmosphere and yet derive no moisturefrom it; while at the same time the driest atmosphere is not devoid ofmoisture, but will part with it under certain conditions. 

Assuming for granted that this relative condition between the plate andatmosphere, disposing the former to receive the humidity of the latter, constitutes the great obstacle the operator has to contend with inproducing, a clear proof upon the plate, the remedy naturally suggestsitself, and is very simple. It consists in merely heating the plateabove the temperature of the atmosphere, previous to polishing, andretaining that temperature during the operation. Various measuresmight be devised to effect the desired object; one of which consists ofa sheet-iron box, heated from the inside by a spirit-lamp, upon the topof which are to be kept the plates ready to undergo the process ofbeing polished; the blocks of the swing or any other vice; or the ironbed belonging to Lewis's vice. 

In cold weather, when it is necessary to keep a fire in the preparationroom, all of the above may be so arranged in the vicinity of the fireas to receive the requisite degree of heat for the purpose specified. 

This part of the subject, however, is left entirely for the ingenuityof the operator. No matter by hat means he accomplishes the object;all that is required is to heat the plate above the temperature of theatmosphere and retain that heat during the process of polishing. 

Since the adoption of this method, in connection with my partner, T. J. Dobyns, even in this humid climate of ours, when everything in the roomis dripping with moisture, it has been attended with invariable success. 

CHOICE OF PLATES, ETC. 

In the great catalogue of complaints made by operators, none is morecommon than that alleged against the quality of plates in general use. Although the greatest diversity of opinion exists upon this subject, nevertheless the plates of every manufactory share in this universalcondemnation. 

To be sure it cannot be denied but that this necessary article ofutility in the photographic art has undergone a sad deterioration inquality owing to the increasing demand and great reduction inprice--the plates of the present day being by no means so heavilycoated with silver as formerly--but the complaint alluded to is notpredicated so much upon the thinness of silver as upon a mysterioussomething which has conferred upon the plates the epithet of not good. 

That this complaint is in a great measure groundless appears evidentfrom the fact that while, with the same brand of plates one operatorcan work successfully, another encounters the greatest difficulty;while one is able to produce beautifully clear and altogethersatisfactory results, the other labors under the troublesome annoyanceof innumerable specks, large dark insensitive patches and brownmap-like portions, together with divers other blemishes, sufficient toprevent him from obtaining anything like a tolerable impression. 

From this wide difference in the results of the two operators usingidentically the same article, it is but reasonable to conclude that thecomplaint is founded in error; while the inference is no more thanjust, that the fault may be traced to a want of practical skill on thepart of the complaining operator himself; rather than to the inferiorquality of the plates. 

The question, then, whether the plates are unfit for use, or whetherthose who pronounce them so understand how to use them, appears to besatisfactorily answered. It therefore becomes a matter worthy ofinvestigation, to ascertain what superior judgment and skill oneoperator possesses over another which enable him to work successfully aquality of plate, pronounced by the other entirely useless. 

Suppose we make a critical examination of one of the repudiated plates. From its external appearance we have little hesitation in pronouncingit to be French; indeed, this presumption is strongly corroborated bythe fact that it is ornamented upon one of its corners with a brand todesignate the manufactory from which it emanated. 

Upon close inspection we cannot fail to notice a striking peculiarityupon the surface; the roughness is very remarkable; the planishinghammer has left amazingly visible indications of its busy work. Onewould suppose the manufacturer intended the surface of the plate torepresent the undulations of the sea, instead of that smooth and levelcharacter so strongly recommended by M. Daguerre. 

Such a plate necessarily requires at the hand of the operatorconsiderable labor before the surface is in a proper condition toreceive a suitable polish from the buffer. The least reflection in theworld should teach any one that so long as the undulatory charactercontinues upon the surface of the plate, it is in a very imperfectcondition for buffing, because the buffer cannot touch every pointequally; the elevated portions alone receiving a high degree of polishwhile the depressed portion, from their roughness acting as nuclei, gather dust, rouge, and other foreign bodies, so detrimental tosensitiveness. The secret of the superior judgment and skill of oneoperator over another, is intimately connected with this point: hissuccess depends very much upon the first process of cleaning the plate. 

Let us examine the manipulation of the complaining operator. He takesone of these plates and gives it a careful scouring with rotten-stoneand alcohol or any other liquid preferred for this part of theoperation--that is, he gives it what he terms a careful scouring--verygently indeed because, from the frequent trials he is in the habit ofmaking in the camera, he fears he will rub the silver entirely awaybefore he succeeds in obtaining a good impression. The dark patches, specks, and granular appearance resulting entirely from the unevennessof the surface of the plate, look like copper to him, and he issurprised that he should have rubbed away the silver so soon, particularly by such delicate handling. 

The judgment and experience of the successful operator, however, teachhim that scouring injures a plate less than buffing. He knows thatunless the hammer marks be obliterated, he cannot by the buffer producea surface of uniform polish and sensitiveness, without which a fairproof is extremely doubtful; he knows that the time employed in thepreliminary operation of cleaning the plate properly is economy. 

There is a style of French plates in the market, denominated heavy, which are truly excellent, if properly managed. Much patience, however, is required to remove the marks of the hammer; but withtripoli and alcohol the surface is readily cut down, and the plate isthen susceptible of a beautiful black lustre by polishing with thebuffer. The complaining operator could not succeed by his own methodwith one of the plates; he would encounter all manner of clouds andother unaccountable phenomena; he would imagine this plate entirelyworn out before it was half cleaned, and soon fix in his own estimationthe reputation of the heavy plate. 

In making a choice of plates, therefore, it would appear to be a matterof perfect indifference with an experienced operator what kind he woulduse, except so far only as the labor required in cleaning them was tobe taken into consideration. 

The distinction between a scale plate, a Scovill No. 1, S. F. , heavy A, star, crescent, eagle, or any other brand, consists in the superiorfinish of some, and the thinness of the silver in the cheaper qualities. 

Consequently, let the complaining operator but employ the diligenceinculcated in this article, to clean his plate thoroughly, so as tobring it to a perfectly even and level surface, and he will seldom betroubled with specks, clouds, dark patches, and the host of otherobstacles which heretofore have tormented him. 

CHAPTER VI. 

AN ACCOUNT OF WOLCOTT AND JOHNSON'S EARLY EXPERIMENTS, IN THEDAGUERREOTYPE. BY JOHN JOHNSON. 

[From Humphrey's Journal, vol. Ii 1851]

As a general thing, however perfect any invention may be deemed by theinventor or discoverer, it falls to the lot of most, to be the subjectof improvement and advancement, and especially is this the case withthose new projects in science which open an untrodden field to the viewof the artisan. Such has been, in an eminent degree, the case with thediscovery first announced to the world by Mons. Jean Jaques ClaudeDaguerre, of Paris, in the year 1839, and which excited unboundedastonishment, curiosity and surprise. It may be questioned had anyother than Daguerre himself discovered a like beautiful combination, whether the world would have been favored with details exhibiting somuch care, patience and perseverance as the Daguerreotype on itsintroduction. Shortly after, these details reached the United States, by Professor S. F. B. Morse, of New York, who was, at the time of thediscovery, residing in Paris. By this announcement, the wholescientific corps was set in operation, many repeating the experiments, following carefully the directions pointed out by Daguerre, as beingnecessary to success. Among the number in the United States, wasAlexander S. Wolcott (since deceased) and myself; both of this city. On the morning of the 6th day of October, 1839, I took to A. Wolcott'sresidence, a full description of Daguerre's discovery, he being at thetime engaged in the department of Mechanical Dentistry, on some workrequiring his immediate attention, the work being promised at 2 P. M. That day; having, therefore, no opportunity to read the description forhimself (a thing he was accustomed to do at all times, wheninvestigating any subject). I read to him the paper, and proposed tohim that if he would plan a camera (a matter he was fully acquaintedwith, both theoretically and practically), I would obtain the materialsas specified by Daguerre. This being agreed to, I departed for thepurpose, and on my return to his shop, he handed me the sketch of acamera box, without at all explaining in what manner the lens was to bemounted. This I also undertook to procure. After 2, P. M. , he had moreleisure, when he proceeded to complete the camera, introducing for thatpurpose a reflector in the back of the box, and also to affix a plateholder on the inside, with a slide to obtain the focus on the plate, prepared after the manner of Daguerre. While Mr. Wolcott was engagedwith the camera, I busied myself in polishing the silver plate, orrather silver plated copper; but ere reaching the end preparatory toiodizing, I found I had nearly or quite removed the silver surface fromoff the plate, and that being the best piece of sliver-plated copper tobe found, the first remedy at hand that suggested itself, was aburnisher, and a few strips were quickly burnished and polished. Meantime, the camera being finished, Mr. Wolcott, after reading forhimself Daguerre's method of iodizing, prepared two plates, and placingthem in the camera, guessed at the required time they should remainexposed to the action of the light; after mercurializing each in turn, and removing the iodized surface with a solution of common salt twosuccessful impressions were obtained, each unlike the other!Considerable surprise was excited by this result, for each plate wasmanaged precisely like the other. On referring to Daguerre, noexplanation was found for this strange result; time, however, revealedto us that one picture was positive, and the other negative. On thissubject I shall have much to say during the progress of the work. Investigating, the cause of this difference occupied the remainder ofthat day. However, another attempt was agreed upon, and theinstruments, plates, etc. , prepared and taken up into an attic room, ina position most favorable for light. Having duly arranged the camera, I sat for five minutes, and the result was a profile miniature (aminiature in reality, ) or a plate not quite three-eighths of an inchsquare. Thus, with much deliberation and study, passed the first dayin Daguerreotype--little dreaming or knowing into what a labyrinth sucha beginning was hastening us. 

[Description of apparatus represented on pages 192 and 199:]

 A. --The Box--about 4 inches long by about 2 outside diameter. B. --The Reflector soldered to a brass screw, and mounted in the rear of the box. C. --The slide to regulate the focus to the plate holder. D. --The standard to the plate holder screwed to the slide. F. --The plate-holder frame having two small ledges, * *, for the plate to rest upon. 

{192}

 g. --The plate resting upon the ledge. , * *, and kept against the frame by the spring h. The plates used were about 3/8 of an inch square. A. --The window with the sashes removed. 

B and C (p. 199) are large looking-glasses mounted as plain reflectors, the lower one C having rotary motion upon the saddle, resting upon thesill of the window in order to direct the rays of the sun upon thereflector B, at any hour of the day--the vertical motion of thereflector C being necessary, the sun varying in altitude so much duringthe hours most favorable to the production of portraits. The reflectorC was {193} kept up to the required position by the handle lever, upright post and bolts. Reflector B was hinged at its upper end at thetop of the window frame, the only motion being necessary was that whichwould reflect upon the sitter the incident rays from reflector C--thereflector B being kept at the required angle by the connecting lever m, etc. Suitable back-grounds were placed behind the sitter. 

[Illustration: Fig. 12 (amdg_12. Gif)]

The reflector B and C, had frequently to be renewed, the heat of thesun soon destroying their brilliance or power of reflecting, light, before renewing them, however, we resorted to the springing of them, bywhich means their power was increased for a period. 

The camera or reflecting apparatus, invented by Mr. Wolcott, was, fromthe nature of the case, better adapted at that day to the taking ofportraits from life, than any other instruments. After carefullyexamining the camera described by Daguerre, and the time stated asnecessary to produce action for an image, it became evident to the mindof Mr. Wolcott at once, that more light could be obtained (as the fieldof view required was not large) by employing a reflector of short focusand wide aperture, than from a lens arrangement, owing to sphericalaberration and other causes. Many experiments having been tried withthe small instrument figured (p. 199), a reflector for taking portraitsfrom life was determined on, having eight inches diameter, with twelveinches focal distance for parallel rays; this was to admit plates oftwo inches wide by two and a half long Mr. Wolcott having on handreflectors of the right diameter, for Newtonian telescopes, of eightfeet focal distance, resolved (as it was a matter of experiment) togrind down or increase the curve for the focal distance beforenamed--this required time. In the mean time, many plans were pursuedfor making good plates, and the means of finishing, them. As thecompletion of the large reflector drew to a close, our mutual friend, Henry Fitz, Jr. , returned from England, whither he had been on a visit, and when he heard what we were about, kindly offered his assistance; hebeing well versed in optics, and having been before engaged with Mr. Wolcott, in that and other business is offer was gladly accepted--Mr. Wolcott himself having frequent engagement; to fill as operator in thedetails of mechanical dentistry. Thus, by the aid of Mr. Fitz, thereflector was polished, and experiments soon after tried on plates oftwo by tow and a half inches, with tolerable success. Illness on mypart quite suspended further trial for nearly four weeks. 

On my recovery, early in January, 1840, our experiments were againresumed with improved results, so much so as to induce Mr. Wolcott andmyself to entertain serious thoughts of making a business of the takingof likenesses from life, intending to use the reflecting apparatusinvented by Mr. Wolcott, and for which he obtained Letters Patent, onthe 8th day of May, 1840. Up to January 1st, 1840, all experiments hadbeen tried on an economical scale, and the apparatus then made, wasunfit for public exhibition; we resolved to make the instruments asperfect as possible while they were in progress of manufacture. Experiments were made upon mediums for protecting the eyes from thedirect light of the sun, and also upon the best form and material for aback-ground to the likenesses. The length of time required for a"sitting, " even with the reflecting apparatus, was such as to renderthe operation anything but pleasant. Expedients were ever ready in thehands of Wolcott: blue glass was tried and abandoned in consequence ofbeing, at that time, unable to procure a piece of uniform density andsurface: afterwards a series of thin muslin screens secured to wireframes were prepared as a substitute for blue glass. The objections tothese screens, however, were serious, inasmuch as a multiplication ofthem became necessary to lessen the intensity of the light sufficientlyfor due protection to the eyes, without which, the likenesses, otherthan profiles, were very unpleasant to look upon. Most of theportraits, then of necessity were profiles formed upon back-grounds, the lighter parts relieved upon black, and the darker parts upon lightground; the back-ground proper being of light colored material withblack velvet so disposed upon the light ground, this being placedsufficiently far from the sitter, to produce harmony of effect whenviewed in the field of the camera. Other difficulties presentedthemselves seriously to the working of the discovery of Daguerre, toportrait taking--one of which was the necessity for a constant andnearly horizontal light, that the shaded portions of the portraitshould not be too hard, and yet, at the same time, be sufficiently welldeveloped without the "high light" of the picture becoming overdone, solarized or destroyed. In almost all the early specimens of theDaguerreotype, extremes of light and shade presented themselves, muchto the annoyance of the early operators, and seriously objectionablewere such portraits. To overcome this difficulty, Mr. Wolcott mounted, with suitable joints, upon the top of his camera, a large looking-glassor plane reflector, in such a manner that the light of the sun (as astrong light was absolutely necessary), when falling upon the glasscould be directed upon the person in an almost horizontal direction. 

Early in February, 1840, Mr. Johnson, Sen. , (since deceased) sailed forEurope with a few specimen likenesses taken with the instrumentscompleted as above, with the intention of patenting the invention. Onhis arrival a joint arrangement was effected with Mr. Richard Beard, ofLondon, in patenting and working the invention in England. Up toFebruary, 1840, but few friends had been made acquainted with theprogress of the art in the hands of Mr. Wolcott and myself. From timeto time reports reached us from various sources of the success ofothers, and specimens of landscapes, etc. , were exhibited at Dr. JamesR. Chilton's laboratory, in Broadway, much to the gratification of thenumerous visitors and anxious expectants for this most wonderfuldiscovery. Dr. Chilton, Professor J. J. Mapes, Professor J. W. Draper. Professor S. F. B. Morse, all of this city; Mr. Cornelius, Dr. Goddardand others of Philadelphia; Mr. Southworth, Professor Plumbe, andnumerous others were early in the field; all, however, using the samedescription of camera as that of Daguerre, with modification for light, either by enlargement by lens and aperture for light, or by shorteningthe focal distance. 

At a conversational meeting of the Mechanics' Institute, Professor J. J. Mapes being present, a question was asked if any one present couldgive information relative to portraiture from life by theDaguerreotype. Mr. Kells, a friend of Mr. Wolcott and a scientific andpractical man (since deceased), at once marked out upon theblack-board, the whole as contrived by Mr. Wolcott. This gavepublicity to the invention of Mr. Wolcott. Shortly after, ProfessorMapes, Dr. Chilton, and many others, sat for their portraits, and werehighly gratified. Professor Morse also came and proposed to Mr. Wolcott to join him in the working of the invention, etc. 

From this time much interest was manifested by our friends in ourprogress. Rooms were obtained in the Granite Buildings, corner ofBroadway and Chambers street, and fitted for business. The rooms beingsmall, it was soon found impracticable to use the arrangement oflooking-glass, as previously spoken of; a new plan became necessary, tointroduce which, the sashes were removed, {199} and two largelooking-glasses were mounted in proper frames, thus:--

[Illustration: Fig. 13 (amdg_13. Gif)]

Just in front, and between the sitter and {200} the reflector, upon aproper stand, were used those paper muslin screen before described;also screens of tissue paper. These screens, however, when they wereused, required so much time for a sitting, that some other medium, as aprotection to the eyes, became absolutely necessary. The mostplausible thing that suggested itself was blue glass; but, as thiscould not be found, numerous were the expedients proposed by thefriends of the art, who from time to time visited our rooms. At thesuggestion of Professor Mapes (who is ever ready to assist those inperplexity), a trough of plate glass s, about twenty-eight inchessquare in the clear, and from three to four inches thick, was filledwith a solution of ammonia sulphate of copper, and mounted on the frameas in the sketch, which, for a time, answered extremely well; soon, however, decomposition of this solution became apparent from theincreased length of time required for a sitting, although to the eye ofan observer, no visible cause for such long sittings could be pointedout. Professor Mapes being appealed to, suggested that to the abovesolution a little acid be added which acted like a charm--shorteningthe time for a sitting from six, eight, or ten minutes to that of aboutone. Decomposition, however, would go on by the action of light andheat through the solution. New solutions were tried, when the wholewere finally abandoned as being, too uncertain and troublesome. (Thereflecting apparatus R, was placed upon the stand as in the sketch, with a wedge for elevating the camera, between it and the table, toobtain the image properly upon the plate. ) A quantity of blue windowglass was next obtained, and holes drilled through the corners of it, and several sheets were wired together to increase the size, and, whencomplete, was suspended from the ceiling in its proper place, and soarranged that when a person was sitting, this sheet of glass could bemoved to and from, the object of which was to prevent shadows on theface of the sitter produced from the uneven surface of the glass. Thislatter contrivance was used until a perfect plate of glass was procured. 

The number of persons desirous of obtaining, their miniatures, inducedmany to entertain the idea of establishing themselves in the Art as aprofession, and numerous were the applications for information; manypersons paying for their portraits solely with the view of seeing themanner of our manipulations, in order that they might obtaininformation to carry on likeness-taking as a business. 

The reflecting camera being a very troublesome instrument to make, anddifficulties besetting us from every source, but little attention couldbe given to teaching others; and, indeed, as the facts seemed to be atthis time, we knew but little of the necessary manipulations ourselves. In course of time, several established themselves. The first one, after ourselves, who worked the discovery of Daguerre for portraittaking in this city, was a Mr. Prosch; followed soon after by manyothers, in almost all cases copying the reflecting arrangement forlight, as figured above, many using it even after we had long abandonedthat arrangement for a better one. 

Innumerable obstacles to the rapid advance of the daguerreotype, presented themselves almost hourly, much to the annoyance of ourselves, and those dependent upon our movements for their advancement. Amongthe most difficult problems of the day, was the procuring of goodplates. Messrs. Corduran & Co. Were among the first to supply thetrade; at that early day, however, it was a very rare thing, to be ableto procure an even perfect surface, from the fact that a pure surfaceof silver could scarcely be obtained, the manufacturers deeming it toomuch trouble to prepare silver plated copper with pure silver--theresult was, that in attempting to polish perfectly such plated metal ascould be procured, the plates would become cloudy, or colored in spots, from the fact of having more or less alloy, according as more or lessof the silver surface was removed in polishing the plate fit for animpression. To explain more clearly, it was the practice of mostsilver platers to use an alloy for silver-plating. In the reduction ofthe ingot to sheet metal, annealing has to be resorted to, and acidpickles to remove oxides, etc. The number of times the plated metal isexposed to heat and acid in its reduction to the required thickness, produces a surface of pure silver. The most of this surface is, however, so rough as to be with difficulty polished, without in placesremoving entirely this pellicle of pure metal, and exposing a polishedsurface of the alloy used in plating. Whenever such metal was used, very unsightly stains or spots frequently disfigured the portraits. The portrait, or portion of it, developed upon the pure silver, beingmuch lighter or whiter than that developed upon the alloy; it thereforeappeared that the purer the silver, the more sensitive the platebecame. Accordingly, we directed Messrs. Scovills, of Connecticut, toprepare a roll of silver-plated metal, with pure silver; it fortunatelyproved to be a good article, but, unfortunately, a pound of this metal(early in 1840) cost the round sum of $9. Like descriptions of metal, the same gentlemen would be glad to furnish, at this time, for $4. Soonafter this, some samples of English plated metal, of a very superiorquality, came to our possession, and relieved us from the toil ofmaking and plating one plate at a time, an expedient we were compelledto resort to, to command material to meet the pressing demands forportraits. 

Having it now in our power to obtain good plated metal, a more rapidmode of polishing than that recommended by Daguerre was attempted asfollows:

This metal was cut to the desired size, and having a pair of "handrolls" at hand, each plate, with its silvered side placed next to thehighly polished surface of a steel die, was passed and repassed throughthe rolls many times, by which process a very smooth, perfect surfacewas obtained. The plates were then annealed, and a number of platesthus prepared were fastened to the bottom of a box a few inches deep afoot wide, and eighteen inches long; this box was placed upon a tableand attached to a rod connected to the face plate of a lathe, a fewinches from its centre, so as to give the box a reciprocating motion. A quantity of emery was now strewn over the plates, and the lathe setin motion. The action produced wag a friction or rubbing of the emeryover the surface of the plates. 

When continued for some time, a greyish polish was the result. Linseed, when used in the same manner, gave us better hope of success, and the next step resorted to was to build a wheel and suspend it afterthe manner of a grindstone. The plates being secured to the inner sideof the wheel or case, and as this case revolved, the seeds wouldconstantly keep to the lower level, and their sliding over the surfaceof the plates would polish or burnish their surfaces. This, with theformer, was soon abandoned; rounded shots of silver placed in the samewheel were found not to perform the polishing so well as linseed. Buff-wheels of leather with rotten-stone and oil, proved to be farsuperior to all other contrivances; and, subsequently, at thesuggestion of Professor Draper, velvet was used in lieu of buffleather, and soon superseded all other substances, both for lathe andhand-buffs, and I would add, for the benefit of new beginners thatthose who are familiar with its use, prefer cotton velvet. The onlyrequisite necessary is, that the buffs made of cotton velvet should bekept dry and warm. 

The greater number of operators, with whose practice I am familiar, use, for polishing plates, prepared tripoli, imported from France, orBrowne's rotten-stone. The former of these articles is veryobjectionable, inasmuch as there is no positive certainty of beingenabled to procure or make the article of uniform grit--the nature ofthe substance rendering, it impossible to reduce it to varying degreesof evenness, by the well known process of washing, for that purpose, and the burning of rotten-stone changes its chemical nature somewhat, at the same time rendering, this invaluable article harsh and gritty. And especially, no reliance can be placed upon burned rotten stone ifpurchased from those who do not give very great attention and care toits preparation; and the same remarks apply to rouge. 

The best article for polishing Daguerreotype plates is rotten-stone, such as can be procured in any town, prepared after the followingmanner: Procure, say half a dozen wide-mouthed bottles, of suitabledimensions, numbering each from one to six. Put into No. 1 about halfa pound of rotten-stone, and nearly fill the bottle with water. Then, with a proper stick or spatule, mix well the rotten-stone and water;after which, let No. 1 rest for, say one minute, then carefully pouroff into bottle No. 2 (or, what would be better, draw off by a syphon)as much of the floating particles of rotten-stone as is suspended inthe water. Again fill bottle No. 1 with water, agitate it as before, and decant it to bottle No. 2, care being taken to draw off only thesuspended particles of rotten-stone. 

When a sufficient quantity of washings from bottle No. 1 is collectedinto bottle No. 2, a similar process must be gone through, as abovestated, for No. 1; the difference being in the care required, and inthe time allowed between the stirring or mixing the rotten-stone andwater. The floating particles of rotten-stone, after four minutes'subsiding, will be found fine enough for the finest Daguerreotypepolishing required. 

A quantity of such washings may be collected in a large bottle, andallowed to stand a few hours, when all the rotten-stone will havesettled. The water may be poured off and the rotten-stone put into anevaporating dish, and while being dried, must be constantly stirred toobtain an impalpable powder. 

Further washings may in like manner be resorted to for finer qualitiesof rotten-stone. In my practice, I have used the articles at two andfour minutes' settling, and occasionally have prepared it afterstanding for eight minutes. So fine a quality as this, however, isseldom required. In using, rotten-stone, I mix with it, for polishing, fine olive oil, until I obtain a thin paste--and the best of allmethods for polishing (well planished) Daguerreotype plates, is onelike that used for glass by lens polishers; that is, by using a disc orbuff-wheel, and having, a suitable holder by which to secure the plate, and then by pressing the plate against the revolving buff, wellsaturated with the mixed oil and rotten-stone, a very good surface isobtained. A quantity of plates may be prepared in this way, and allthe adhering oil, etc. , may be removed by a clean hand, or lathe buff, after which each plate must be heated to the point necessary to burnoff the remaining oil great care being required not to overheat theplate. A very slight excess of temperature will at once destroy allthe polish previously obtained. The test for ascertaining the righttemperature is at hand; the adhering oil will be driven from the platein the form of smoke when the right temperature is reached. The momentthe smoke ceases to rise from the plate, the heat must be removed, andthe plate quickly cooled upon a piece of iron. 

A quantity of plates thus prepared may be kept on hand for any requiredtime, and the labor of one minute, with a lathe or hand-buff with drycharcoal, or rather, prepared lampblack, will perfectly polish thesurface ready for indexing, etc. This lampblack also requires somecare in preparing. Take a small-size crucible, properly temper it by aslow fire, that it may not be cracked after which, fill it with commonlampblack, cover it over with a piece of soap-stone, and again replaceit in the fire. Build a good hard coal fire around it continue theheat for two or three hours, being careful not to raise the cover tillthe crucible be quite cold. Pulverize when using it. It is verydesirable to keep this lampblack dry and warm. Some operators use muchrouge I would recommend the above in preference; but those who feelthat they cannot dispense with the use of rouge, had better try a largeaddition of prepared lampblack to a small one of rouge, as this latterarticle, unless great pains be taken in its preparation, will adhereand work itself into the body of the surface, so that it cannot beremoved therefrom; and I have seen many specimens of Daguerreotype verymuch injured in effect from this rouge tint disseminated throughouttheir shaded features, at the same time that the whole general effectof such pictures is that of a want of life. It is true that with theuse of rouge a very high degree of polish may be obtained, but probablynot higher than can be produced with many other substances of a lessobjectionable nature. 

From the announcement of the discovery by Daguerre to the beginning ofthe year 1840, I am not aware of any attempt to lessen the time for theaction of an image, or an impression, other than that of the reflectingcamera invented by Mr. Wolcott. Early, however, in 1840, Mr. Wolcottwas desirous to be enabled to further shorten the time for a sitting, and having some knowledge of bromine and its action, by request, Dr. Chilton prepared a small quantity; but Mr. Wolcott did not succeed verywell with it, he having invariably used too much in combination withiodine to produce that sensitive coating now well known to theprofession. Professor Morse, of this city, Dr. Goddard, ofPhiladelphia, and others, in the years 1840 and 1841, were acquaintedwith the use of bromine. N. Griffing, of this city, or myself, usedwith tolerable success, iodine in large excess to nitric acid andwater; and, subsequently, to nitro muriatic acid (which reacted andformed a peculiar chloride of iodine); this latter combination provedto be preferable to simple iodine, at the same time somewhat moresensitive, and was used by me in this city up to the time of my leavingfor London (October 1, 1840). On arriving in London, I instituted aseries of experiments in the various chemical combinations, solely withthe view to be enabled to obtain more speedily a portrait than it waspracticable to do with any known chemicals at that date. The highlatitude, and the winter season of the year rendering but a feeblelight at best, the greater the necessity for a more sensitive chemicalpreparation to the shortening the time for a sitting. Near thebeginning of the year 1841, I discovered and practically applied, chloride of iodine to great advantage, and, as far as memory serves me, I believe the first used in this country was some made and shipped, Messrs. Harnden & Co. , from London, to Mr. Wolcott, in New York. 

About the same time, Mr. John Goddard, of London (who was associatedwith myself), discovered a rather valuable combination of chemicals, consisting of a mixture of iodine, bromine, iodus, and iodic acid, anda proper combination of those bodies gave an action somewhat moresensitive than chloride of iodine--but the "high lights" of theportraits would become solarized or overdone, more frequently with thiscombination than with the chloride of iodine. Throughout the year1841, I used, with great success, chloride of iodine, applied as onecoating--occasionally in conjunction with Mr. Wolcott, attempting theuse of iodine, bromine, and chlorine, and at times with more or lesssuccess. The difficulty of exactly combining, the three elements abovementioned, in order to produce a certainty of result with harmony ofeffect, was the work of many months, with great labor and study, theslightest modification requiring a long, series of practicalexperiments, a single change consuming, frequently, an entire day ininstituting comparisons, etc. , etc. 

Early in the year, 1842, I discovered a combination of chemicals (nowknown in London as "Wolcott's Mixture, " in hermetically sealed bulbs)of exceeding uniform character, very sensitive to the action of light, and specimens produced in 1842-3, with this combination, will bearcomparison with the best specimens produced at this late date. 

About the same time, I discovered that however much overdone aDaguerreotype might be, the means were at hand to save or redeem it. It has long, since been known to operators, that if a plate be exposedto light after being coated, unless it be again coated, a clear anddistinct picture could not be obtained upon the same plate withoutfirst repolishing and recoating the same, care being taken that nolight fall upon the prepared surface. To prevent solarization, coat aplate as usual, expose to the action of light any required time(according to circumstances), say from quarter to one half more timethan would be required in the ordinary method of procedure; observe, before putting the plate in the mercury box, place it over the vapor ofiodine, bromine, or chlorine, etc. (carefully excluding the light), for a very brief period, great care being required to have the selectedvapor very much diluted with air, in order to success. Manyexperiments will be required ere arriving at satisfactory results. Specimens now unknown to general operators, for harmony of effect, havebeen, and may again be produced by the method pointed out above. Ihave found the best general effect, and the most certain result tofollow from the use of the vapor of chlorine--but this requires morethan ordinary care. I would, therefore, recommend the use of iodine. Thus: to a few grains of iodine, add an ounce of warm water (whichwill become tinged with iodine); when cold, to half a pint of purewater in a new and clean coating box, put, of the above, fifty drops;stir and mix well this small quantity of iodine in with the water; inten minutes this box will be ready for use. Great care and judgmentwill be required in the application of this vapor to the plate; if theplate remain over the vapor too long, the developed picture will havea faint and misty appearance; if not exposed long enough, the "highlight" will be solarized. I have great hope of the ultimate use ofthis process, as it is the only means yet discovered to be enabled tosecure specimens of extremes of light and shade, yet producing harmonyof effect; and I would call the attention of the profession to thefact, that a plate may be exposed to the action of light for any lengthof time (a thousand times longer than required to act for the lesserquantity of mercury to deposit itself, or that amount necessary to forma perfect specimen), and be restored by the application of any of thevapors above mentioned, remarking that for extremes for solarization, denser vapors will be required. Much remains to be done with thisdiscovery to the application of the Daguerreotype. 

HUMPHREY'S JOURNAL OF THE DAGUERREOTYPE & PHOTOGRAPHIC ARTS. 

The above-named publication is well known as the best and most valuableone devoted to the Photographic Science in this country. Humphrey'sJournal made its appearance November 1st, 1850, and consequently is thefirst and oldest serial offered to the Photographic world. 

The art of producing Portraits and Landscapes by means of Light, hasrecently taken a new and enlivening impulse, which will in allprobability lead to important and interesting results. No practicalDaguerreotypist, Photographer, or amateur, should be without the meansat hand for securing all of the information upon this subject. Eachshould be ready to receive and apply the improvements as they may bedeveloped. In order to accomplish this, it is a matter of greatimportance to the Practitioner or Experimenter that he should have areliable medium through which he can obtain information. In whatsource can the inquirer better place his confidence than in a regularJournal, whose editor is literally a practical person, and familiarwith the manipulations necessary for producing Portraits upon"Daguerreotype Plates, " and upon glass and paper? Such is theconductor of Humphrey's Journal. 

This Journal is published once every two weeks, and contains all theimprovements relating to the Art, and is the only American Journalwhose editor is practically acquainted with the process for producingDaguerreotypes, Ambrotypes, and Photographs. The first No. Of Vol. X. Is dated May 1st, 1858. The terms (Two Dollars per annum) are triflingcompared with the vast amount of information furnished. 

AMBROTYPES. --Humphrey's Journal contains everything novel which appearsupon this subject, and has already presented more new, important, andoriginal matter than can be found in any other place. 

Many are the letters we have received during the term of the lastvolume, in which the writer has stated that a single number ofHumphrey's Journal has contained information of more value to him than"several times the amount paid for the entire volume. "

Our resources have grown up around us, and our facilities forprocuring, as well as distributing, all such facts and improvements aswill benefit as well as instruct all who have the progress of the Artat heart, are as ample as they can well be made. 

The future volumes will be abundantly furnished with original writingsfrom persons of standing in the scientific world; and the practicalPhotographer will here find a full account of such improvements as mayfrom time to time develop themselves. 

From the editor's long practical experience in the HeliographicScience, he will be enabled to present the subject in a plain, clear, and concise manner. 

Read what the Editors say of Humphrey's Journal:--

"We have received a copy of a valuable Journal (Humphrey's) publishedin New York, which has reached the 18th number of Vol. VI.... We nowhave the pleasure of quoting from our trans-atlanticcoadjutor. "--Liverpool Photographic Jour. 

"Humphrey's Journal is practical as well as scientific incharacter. "--American Journal of Science and Arts. 

"It treats the subject knowingly and with force. "--New York Tribune. 

"It is both a popular and interesting publication. "--Mechanics'Magazine. 

"It is highly useful to all who practice 'shadow catching. '"--OhioState Journal. 

"The work is neatly gotten up, and contains many interesting varietiesin this new field of science. "--Times. 

"It should be hailed and encouraged, not only by Daguerreotypiststhemselves, but by every lover of Science and Art. "--The Democrat. 

"We cannot too strongly urge all artists, and those persons who feel aninterest in the Heliographic Arts and Sciences, to take a copy of thework. "--Sentinel. 

"It is indicative of talent worthy of the important Art it is designedto elevate. "--American. 

"This Art is entitled to its own organ, which could not have falleninto better hands than those of the editor of 'Humphrey'sJournal. '"--Transcript. 

"It is a scientific work of interest and usefulness. "--Star of theNorth. 

"This Journal answers many points heretofore regarded asinexplicable. "--Hudson River Chronicle. 

"It is rich with interest. "--North American. 

"It contains all the 'Improvements. '"--Delta. 

"It teaches us how to take our own portraits. "--Bee. 

"It will cultivate a taste for Daguerreotypes. "--Commercial Advertiser. 

"It should be in the hands of all. "--Reveille. 

"It is the Daguerreotypist's friend. "--London News. 

"It should be found in every library. "--Evening Journal. 

From some of our Subscribers

"Humphrey's Journal has been the means of saving much time and money, for by its instruction I have been enabled to produce some of thefinest Paper Pictures I have ever seen. " W. P. 

"Don't fail to send me the Journal, for I would not be without it forfive times the amount of subscription. It is the only publication Ican depend upon. " A. G. R. 

"Your treatment of the humbugs and humbugging members of theprofession, is of the most valuable importance to us practicalDaguerreans. Go on. God speed! Here is the amount for the renewal ofmy subscription. " E. F. S. 

"How can any Operator afford to be without it?" L. L. H. 

"Here are five dollars: send me Humphrey's Journal to this amount. Iwill not be without it. " M. S. 

"It is my best friend. " J. E. W. 

We might quote like commendatory extracts enough to more than ten timesfill this page. 

Humphrey's Journal contains 16 octavo pages of reading matter. 

TERMS. 

 One copy per annum, in advance . . . . . . $2 00 Three copies, do. Do. . . . . . . $5 00 Six copies, do. Do. . . . . . . $9 00

The thousands who read it cannot be induced to remain without it. Allwho desire to keep up with the improvements should subscribe for a copy. 

Subscription price Two Dollars per year. 

Don't fail to become a subscriber. Address

 S. D. HUMPHREY Office, 37 Lispenard Street, NEW YORK. 

 THE PRACTICAL MANUAL OF THE COLLODION PROCESS. BY S. D. HUMPHREY. THIRD EDITION

This Edition contains all the Improvements in the Art made public up tothe day of publication, and gives complete Practical Instructions formaking Collodion Positives or Ambrotypes, Collodion Negatives, Printing, etc. , etc. The quick, great and unprecedented sale of thefirst and second editions demonstrates, more than the strongestlanguage could possibly do, the extraordinary and increasing popularityof this work. The Third Edition contains two hundred and sixteen 12mo. Pages, of a larger size and in smaller type than either of thepreceding editions, and is illustrated with numerous wood-cuts. It isintended to be the best practical work extant; substantially bound incloth, price One Dollar; forwarded by mail (postage prepaid). Address

S. D. HUMPHREY, New York

A GUIDE TO PHOTOGRAPHY, Containing simple and concise directions for obtaining Views, Portraits, etc. , by the chemical agency of Light, by W. H. Thornthwaite, author of "Photogenic Manipulations, " etc. Illustratedwith numerous wood-cuts. The Book contains more than one hundred 12mopages, bound in board, and is sold at twenty-five cents per copy, orfive copies for one dollar. Address

S. D. HUMPHREY, New York

 HOLMES, BOOTH & HAYDENS, MANUFACTURERS OF DAGUERREOTYPE CASES, PLATES, CAMERAS, MATTINGS, PRESERVERS, ETC. , ETC. 

MANUFACTURERS AND IMPORTERS OF EVERY VARIETY OF AMBROTYPE, ANDPHOTOGRAPHIC GOODS, Of the Best and most approved Quality. 

ESPECIAL ATTENTION GIVEN TO THE FURNISHING OF EVERY ARTICLE USED IN THEPRACTICE OF THE DAGUERREOTYPE

Depot 81 Chambers and 63 Reade St. , New York. 

Manufactory at Waterbury, Conn. 

HOLMES, BOOTH & HAYDENS' CAMERAS

From 1/4 to the Mammoth size. These CAMERAS are of the most superiormake, and all subjected to the most thorough test before being offeredfor sale. 

VIEW CAMERAS, made expressly for taking views: an entirely new article. 

DAGUERREOTYPE PLATES, OF EVERY VARIETY, AND WE WOULD CALL PARTICULARATTENTION TO THE

Wreath, and H. B. & H. Eagle 40 Plates, AS HAVING NO EQUALS IN THEMARKET. 

SOLE AGENTS FOR THE CELEBRATED H. B. AND N. P. FRENCH PLATES. 

Always on hand a complete assortment of Ambrotype and Photographicgoods. 

SOLE AGENTS FOR THE Patent solid glass corner Plate Holders. 

All orders will receive prompt attention, and be forwarded withdispatch. 

 HOLMES, BOOTH & HAYDENS, 81 Chambers, and 63 Reade St. New York. 

SCOVILL MANUFACTURING CO. 

 MANUFACTURER OF DAGUERREOTYPE PLATES, MATTINGS, PRESERVERS, CASES, APPARATUS, etc. , etc. 

Importers and Dealers in every description of Daguerreotype, Photographic, AND AMBROTYPE GOODS, The SCOVILL MANUFACTURING COMPANY flatter themselves that an experienceof nearly twenty years in the business and the most extensive varietyof the above Goods in the United States, entitle them to thecontinuance of orders for the Domestic and Foreign trade, which willreceive the most careful attention. 

Park Building, New York. Entrances--36 Park Row, 4 Beekman, and 141Nassau Street. 

SCOVILL MANUFACTURING CO. 

Would call especial attention to their large variety of

CASES, Embracing many Fancy Styles made only by themselves, and to which theyare constantly adding New Designs. 

 Union Cases, Of all sizes, with Riveted Hinges. AGENTS FOR THE SALE OF C. C. HARRISON'S CAMERAS, with improvements, which we are now prepared to sell at reduced prices, and warranted to give better satisfaction than ever beforeDAGUERREOTYPE PLATES, H. B. --N. P. --Star and other brands PLATE GLASS, embracing three-quarters white: Crown and all other varieties. Wewould call particular attention to our Black Glass, made expressly forAmbrotypes. 

 CHEMICALS, for the Daguerreotype and Photographic Art. Iodized and Plain COLLODION. Gun Cotton, etc. , etc. Tagliabue's Collodiometres and Actino-Hydrometres, for testing Chemicals. 

APPARATUS OF EVERY VARIETY. 

Gutta Percha, Porcelain, and Glassware of all kinds used in the Art. 

A large assortment of Gilt Frames always on hand and made to order. 

Ambrotype Shields, with solid corners of a new style. 

All orders will meet with prompt attention

 SCOVILL MANUFACTURING CO. , PARK BUILDING New York 36 Park Row, 4 Beckman, and 141 Nassau Street. 

 HARDWICH'S PHOTOGRAPHIC CHEMISTRY AMERICAN EDITION. 

 A MANUAL of PHOTOGRAPHIC CHEMISTRY, INCLUDING THE PRACTICE OF THE COLLODION PROCESS. 

BY

T. FREDERICK HARDWICH, LECTURER ON PHOTOGRAPHY IN KINGS COLLEGE, LONDON; LATE DEMONSTRATOR OF CHEMISTRY IN KING'S COLLEGE. 

Last Edition, The above is the title of this new and valuable work. It is too wellknown to need any further comment in this place. This volume containsnearly 300 large duodecimo pages, bound in red cloth, $1. 00. Copiesto be forwarded by mail, $1. 18, postage pre-paid. 

 S. D. HUMPHREY, Photographic Book Publisher, 37 LISPENARD STREET, NEW YORK, N. B. Postage stamps taken.