Page:Proceedings of the Royal Society of London Vol 1.djvu/272

Rh conﬁned to the freedom of motion it gives to the particles, but to the exaltation of the electrical energies of bodies, such as is Well known to take place in glass, tourmalin, and sulphur. The electricity of an insulated plate of copper, and a plate of sulphur, was scarcely sen— sible at 56° Fahr. to the condensing electrometer; at 100‘J they affected the gold leaves Without condensation; they increased in a still higher ratio as the sulphur approached its melting point; and at a little above that point, the two substances rapidly combine, and evolve heat and light. In general, when the different electrical ener- gies are equally strong, the combination seems to be vivid, the heat and light intense, and the new compound is in a neutral state, as in combustion, and the union of the strong acids with the alkalies; but when only the energy is strong, the effect is less vivid, and the com- pound exhibits the excess of the stronger energy.

Mr. Davy then considers the theory of the Voltaic apparatus; and remarks, that the above facts seem to reconcile Volta’s own theory with the chemical theory of galvanism.

In a pile of zinc, copper, and water. the plates are in opposite states of electricity; and in regard to such low electricity, the water is an insulating body. 01' course, each plate produces an opposite electricity upon the opposite plate, the intensity increasing with the number, and the quantity with the extent of the series. Upon con- necting the extreme points, the opposite electricities tend to produce an equilibrium, which would cause the motion to cease : but the ﬂuid medium being composed of two elements possessing opposite electrical energies, the oxygen is attracted by the zinc, and the hy- drogen by the copper. Hence the balance of power is only momen- tary; for oxide of zinc is formed, and hydrogen is disengaged. The electricity acquired by the copper is communicated anew to the zinc, and the process continues as long as the chemical changes are carried on.

Neither the conducting nor solvent powers of the ﬂuid mediums are a principal cause of their activity; for strong sulphuric acid has very little activity in the pile. The effect of neutro-saline solutions diminishes when troughs are used, according as their acid arranges itself on the side of the zinc plates, and their alkali on the other; but the energy may be restored by agitating the ﬂuids in the cells.

As sensible heat appears when an equilibrium is produced by small metallic surfaces in the voltaic battery, the opposite states being exalted, so if the decomposition of the chemical agents be essential to the balance of the opposed electricities, the decomposition of the saline solutions ought to be attended with an increase of temperature. To water electriﬁed in the gold cones by the power of 100 plates, a drop of solution of potash was added in the positive cone: potash immediately passed over, and in less than two minutes the water was in a state of ebullition. When solution of nitrate of ammonia was employed, the water was evaporated in three or four minutes with a kind of explosive noisc, and inﬂammation took place. The pure alka-