In order to prove the identity of electricities derived from different sources, the author in this communication, after viewing the phenomena exhibited by electricity, shows, that although some effects are most readily derived from a particular source, yet none are peculiar to such source. The principal points in which ordinary and voltaic electricity have been considered to differ, are the inefficiency of ordinary electricity to produce chemical decomposition, or to affect a magnetic needle like voltaic electricity. The experiments of Wollaston were made early in the application of electricity to chemical decomposition, before the general law of the transfer of the elements to the poles of the battery had been indicated; yet his 4th experiment, in which electricity from the machine was passed through a solution of sulphate of copper, and his 5th, where it was passed through a solution of corrosive sublimate, have the true characteristic of decomposition by voltaic electricity: and it is surprising that those who advocate a distinction between these electricities should have ventured to overlook these experiments, when they bring forward the experiment of the decomposition of water, as deficient in this characteristic of the transfer of the elements. This circumstance, however, induced Mr. Faraday not merely to repeat Wollaston’s 4th experiment, which he did with complete success, but to adopt different arrangements and by these, with ordinary electricity, he obtained, in various instances, chemical decompositions having all the characters of decomposition by voltaic electricity. Whatever doubt, therefore, may have been thrown upon this part of the subject, he has entirely removed it. The author has also removed the doubts which it appears had been entertained respecting the conclusion of M.Colladon, in consequence of the failure of his experiments in the hands of others. By a particular arrangement connected with the glass inclosing the galvanometer, and by retarding the passage of the electricity through its wires, by means similar to those by which gunpowder is roost successfully exploded by an electric discharge, which he also employed to effect chemical decomposition, Mr. Faraday succeeded in causing the needle to deviate, both by the discharge of a battery, and by electricity passing directly from the conductor of the machine. In justice to M. Colladon, we must remark, that the account which he gives of his experiments affords no reasonable ground for doubting the accuracy of his conclusions: the details are clear, and the numerous results unequivocal. We may also notice, that, in the same memoir, M. Colladon gives an account of some very interesting experiments, made with a similar arrangement, on the magnetical effects of atmospherical electricity, by which its power of causing deviations of the needle is satisfactorily established.
Chemical decomposition of water into hydrogen in heterogeneous aluminium-containing compositions
