Download and read  "An Elementary Treatise On Electricity" by Maxwell James Clerk

...mineral products, and several substances have been known by the name of magnesia besides that which modern chemists know by that name. The loadstone, the touchstone, and meerschaum, seem however to have been the principal substances which were called Magnesian and magnetic, and these are generally understood to be Lydian stones. 3. ] ELECTRIFICATION OF A CONDUCTOR. 3 It will be found that the tray is now electrified. Shreds of paper or gold-leaf placed below it will fly up to it, and if the knuckle is brought near the edge of the tray a spark will pass between the tray and the knuckle, a peculiar sensation will be felt, and the tray will no longer exhibit electrical phenomena. It is then said to be discharged. If a metal rod, held in the hand, be brought near the tray the phenomena will be nearly the same. The spark will be seen and the tray will be discharged, but the sensation will be slightly different. If, however, instead of a metal rod or wire, a glass rod, or stick of...