IB 14.] On the Hypotheses of Galvanism, 87 



certain degree of rapidity. 3. That the oxide is removed so as to 

 expose a fresh surface to the fluid. If acids be employed, those are 

 the best that dissolve the oxide ; or if neutral salts, those which 

 form triple salts with the oxide which is pioduced. The chemical 

 hypotiiesis affords a plausible method of accouniiiig for the different 

 effects of the apparatus, whether we use large or small plates ; for 

 it is not unreasonable to suppose that the electricity will become 

 more intense or concentrated at every successive transmission 

 through a new oxidating surface, while its absolute quantity depends 

 upon the amount of oxide that is formed. 



With respect to the experiments of Bennett, or others of a 

 similar kind, which have been adduced in favour of the electrical 

 hypothesis, it is probable that Volta has been mistaken in his 

 Hpi^lication of them, and of the principle to which they should be 

 referred. Instead of supposing, as he does, that all metals are 

 naturally in tlie same state of electiicity, and that, by being placed 

 in contact, a portion of it is attracted from one to the other, the 

 facts would seem to indicate that the reverse takes place ; and that 

 although the electricity of each individual metal is in equilibrio 

 with tlie atmosphere, yet that it is unequal with respect to each 

 other ; that zinc, for example, is negative with respect to copper. 

 When they are placed in contact, their electricity is equalized ; but 

 when they are again separated, the zinc, having acquired a portion 

 of electricity from the copper, becomes positive with relation to 

 the atmosphere ; and the copper, for the same reason, negative. 



The effect that takes place in the interrupted circuit, between 

 the e.Ktremities of the pile, consists in the decomposition of the 

 interposed substance, and in the diecharge of its constituents from 

 the two wires. If we take water as an example, and wires are 

 employed which arc not acted upon by tlie substances liberated, we 

 find that the fluid diminishes in bulk, while from one end oxygen 

 is discharged, and from the other hydrogen, and these in the pro- 

 portion requitite to form water. 1 made an attempt to analyse the 

 nature of tin's operation, by supposing that when electricity is dis- 

 charged from the wire connected with the positive end of the pile, 

 it unites itself to a portion of hydrogen, in order to pass across the 

 fluid to the negative extremity. For this purpose it decomposes a 

 quantity of the water contiguous to the wire, and liberates the 

 oxygen ; and after passing across the fluid in connection with the 

 hydrogen, it discharges the iiydrogcn upon entering the negative 

 wire. * A different principle was advanced by Hesingcr and Ber- 



• Nidi. Jour. iii. 9. Long after tlic |nil>licalion of my former remarks on 

 fiJilvanism, 1 met willi a pinsagc in the- Joiini;;l dc Plivsiquo, wliirli proves that 

 a very ^imilar idea had occurred to MM. I'uuicroy, Vaiii|iieliii, and Thcnard. M. 

 Delaini; herie, w lio writes the article, sa\t, tliat tliese |)hilo^ioi)hcr* Mii>))0>.ed lh.if. 

 tlie electricity jia'^seb frorii tlie iiosilive to the iie(;ativc u ire, dccom|io).es llie water, 

 leaves the oxygen, and carries llie li\dri>e;en to the iie;;;itive wire, wlieic it leaves 

 it.(n) It is not stated whence this opinion ib derived, nor have 1 licen lihle t« 

 ■scer'.ain thi» point. See also boine obicivuliuuk of Mr. Ciilhberlson's. (A) 



(a) Jour, de IM73, liv. 1 J. (4) Ni-.U. J-nr. ii. 'iHl^ 



