Chap. VI Experiments on the Deflagration of Metals by the Galvanic Pile
The pile with which these experiments were made consisted of thirty-six plates of silver, and an equal number of zinc ones, between which were interposed disks of flannel, moistened with a solution of the muriate of ammonia.—Each plate had a diameter of ten inches, or contained 78.58 square inches;—consequently the whole surface of silver in the pile, reckoning only one side, was 2828.57 square inches, and that of zinc the same.
With this instrument, in December 1801, gold, silver, copper, tin, lead and zinc were deflagrated with surprising facility. The gold burned with a vivid white light, inclining a little to blue, and deposited an oxyd of a deep purplish-brown colour.—The silver gave a vivid flame of a greenish hue, and extremely brilliant. Its oxyd was of a blackish colour. The copper presented phenomena similar to those which attended the gold.—Lead gave a very vivid light, of a dilute bluish purple.—The tin afforded a light similar to that of the gold, but burnt with much less energy; probably because the leaves were thicker. The zinc gave a blueish white flame, which was edged, at the moment of contact, with red. It was more difficult to inflame than any of the preceding metals, but the leaves were likewise much thicker. The oxyds of the four last metals were not examined.
Water was poured upon the upper plate of the pile, so as to form a standing pool; and several pieces of the same kind of metals with those before experimented upon, were presented to the plate through this aqueous medium, and were deflagrated. They afforded a flame of the same colour as when they were brought to the bare plate.—A vapour was sometimes perceptible immediately after the deflagration, and was supposed to arise from a portion of water converted into steam by the intense heat.
It is very remarkable that the shocks taken from this pile, which produced such astonishing effects upon metals, could be received with but very trifling inconvenience, through the human body.
Besides these experiments, which were made by a society of gentlemen, a variety of others were performed, from which nearly the same conclusions were deduced.—Two other facts, however, deserve notice.
1. When metallic leaves are deflagrated in carbonic-acid gas, the flame is weak: but when in oxygen gas, the communication between the upper and under plates of the pile is no sooner formed, than the metallic leaves are destroyed with one sudden flash.
2. When metals are subjected to Galvanism in an exhausted receiver, they emit light but are not oxydated.