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.
CHAP. VII.
Further Galvanic Experiments on Metals, and on other Substances.
It is hardly necessary to mention, that every experiment made by means of the Galvanic pile may be performed, with equal success, with the trough. The experiments related in this chapter may be effected by the pile, but they cannot be done with the same convenience as when troughs are used. The battery[[19]] employed in these experiments consisted of sixty pieces of silver, and a like number of zinc, each two and a quarter inches square. The shock produced by this trough, by means of two metallic conductors, was distinctly felt in the shoulders, and the contraction or spasm was so violent, as to render the operator unable to hold the conductors, when in contact with the plates by which the trough terminated each way.—A sensation resembling that produced by hot water, was at the same time felt in the wrists and fore-arm.
A small steel wire, which was used for the conductor to form the communication, upon its contact with the plates, produced a vivid spark and bright scintillations.—When a piece of phosphorus was placed upon the end of this wire, and made a part of the circuit, it was instantly inflamed.
Another battery of the same size being connected with the one above described, gun-powder was fired, and gold leaf deflagrated without any perceptible residuum—being probably volatilised by the heat occasioned by the experiment.
Mr. Davy, secretary of the Royal Society, placed a small piece of pure potash (which had previously been exposed to the atmosphere, so as to render it a conductor of the Galvanic fluid,) upon an insulated plate of platina, connected with the negative[[20]] end of a battery, of the power of two hundred and fifty plates, six inches by four, in a state of intense activity.—A wire communicating with the positive end, was brought in contact with the upper surface of the alkali. The whole apparatus was in the open air. Under these circumstances a vivid action was soon perceived.—The potash began to fuse at both points where the fluid acted upon it.—There was a violent effervescence at the upper surface:—at the lower or negative surface there was no liberation of elastic fluid, but there appeared small metallic globules, very much resembling quick-silver. Some of these globules burned with an explosion and a bright flame, as soon as they were formed, while others remained which were merely tarnished; and finally a white film was formed over their surfaces, which was afterwards found to be pure potash.