[144] The appearance of acid and alkaline matter, in water acted on by a current of electricity, at the opposite electrified metallic surfaces, was observed in the first chemical experiments made with the column of Volta--(see Nicholson’s Journal, vol. iv. p. 183, and vol. iv. p. 261, for Mr. Cruickshank’s Experiments; and Annales de Chimie, tom. xxxvii. p. 233, for those of M. Desormes): _On some Chemical Agencies in Electricity_: by Sir Humphry Davy.--Philosophical Transactions for 1807. The various theories of electro-chemical decomposition are carefully stated by Faraday, in his fifth series of _Experimental Researches on Electricity_, in which he thus states his own views:--“It appears to me that the effect is produced by an _internal corpuscular action_ exerted according to the direction of the electric current, and that it is due to a force either _superadded to_ or _giving direction to the ordinary chemical affinity_ of the bodies present. The body under decomposition may be considered as a mass of acting particles, all those which are included in the course of the electric current contributing to the final effect; and it is because the ordinary chemical affinity is relieved, weakened, or partly neutralized by the influence of the electric current in one direction parallel to the course of the latter, and strengthened or added to in the opposite direction, that the combining particles have a tendency to pass in opposite courses.” [145] “This capital discovery (chemical decomposition of electricity) appears to have been made in the first instance by Messrs. Nicholson and Carlisle, who observed the decomposition of water so produced. It was speedily followed up by the still more important one of Berzelius and Hisinger, who ascertained it as a general law, that, in all the decompositions so effected, the acids and oxygen become transferred and accumulated around the positive, and hydrogen, metals, and alkalies around the negative, pole of a voltaic circuit; being transferred in an invisible, and, as it were, a latent or torpid state, by the action of the electric current, through considerable spaces, and even through large quantities of water or other liquids, again to reappear with all their properties at their appropriate resting-places.”--_Discourse on the Study of Natural Philosophy_: by Sir John Herschel, Bart., F.R.S. [146] Numerous beautiful illustrations of this fact will be found in Becquerel’s _Traité Expérimental de l’Électricité et du Magnétisme_.