III. Experimental contributions to the theory of electrolysis

In July 1800 Nicholson and Carlisle first effected the decomposition of water by the pile of Volta; and they were not a little surprised when the constituent gases of the water appeared separately at some considerable distance from each other, but they offered no opinion as to the cause of so singular a phenomenon. A little later Cruickshank also decomposed water by the pile, and, for the first time, many metallic salts f. He also, like Nicholson and Carlisle, was much struck by the appearance of the compounds round poles separated some distance, and attempted to explain the phenomenon by supposing that the principle of galvanism could exist in an oxygenated and deoxygenated condition that in entering water at the negative end, it combined with oxygen, liberating hydrogen, and that on arriving at the positive end the oxygen either escaped or combined with the wire. This hypothesis, which involves the idea of an imponderable capable of combining with ponderables, underwent various modifications by Fourcroy and Vauquelin and Thenard, and by Dr. Bostock and others.