Peculiar Voltaic Arrangements. 141r 



we may take it as a certain fact that one portion of the oxy- 

 gen of the peroxides, that chlorine, and bromine are bodies 

 which act in the same manner npon water, we do not know 

 for all that the way in which they excite a current ; or ra- 

 ther we do not know why any of the three substances first 

 named acquire, under certain circumstances, the power of 

 decomposing water. According to the views of De la 

 Rive and some other electricians, the cause of the currents 

 produced by hydro-electric circles is chemical action. Con- 

 vinced as I am of the general truth of the principle laid 

 down by the piiilosopher of Geneva, I cannot help doubting 

 the correctness of that doctrine of his according to which 

 chemical action must always precede the appearance of a cur- 

 rent. As far as I understand the chemical theory of galvan- 

 ism alluded to, it cannot account for the disturbance of the 

 electric equilibrium which takes place within a voltaic circle 

 formed out of such substances as do not chemically act upon 

 each other under ordinary circumstances. Amalgamated or 

 distilled zinc not being attacked by acidulated water, perox- 

 ide of lead not being acted upon by nitric acid, bromine or 

 chlorine not decomposing water, ought not, according to 

 De la Rive's hypothesis, to excite any current if arranged 

 so as to constitute with platina a voltaic circle. In asserting 

 that the theory in question cannot account for the currents 

 which are excited by the last-mentioned arrangements, I am 

 well aware of what Mr. De la Rive has brought forward 

 with the intention of vindicating the correctness of his views. 

 He maintains, that in the cases above slated there is some 

 feeble chemical action taking place, and that it is this action 

 which must be considered as the cause of the initial current. 

 This current being the effect of a chemical action, becomes, 

 according to the opinion ofDelaRive, itself the cause of an ad- 

 ditional current by effecting electrolyzation, &c. [Itecherches stir 

 la cause de VElectricite Voltaique, 1836, p. 128.) Ingenious 

 as these views may be, I cannot convince myself of their 

 truth until Mr. De la Rive has given proofs more decisive than 

 those are which he has hitherto oflered in favour of his as- 

 sertion, made either explicitly or implicitl}', that it is only a 

 film of hydrogen which protects amalgamated zinc against the 

 action ot acidulated water; that peroxide of lead nnd nitric 

 acid do chemically act upon each other; that chlorine is ca- 

 pable of decomposing water in darkness, &c. But if no such 

 chemical actions take place in the cases mentioned, and if 

 nevertheless chemical action be the real cause of hydro-elec- 

 tric currents, how are we to account for the excited currents 

 in question ? We know as yet very little indeed of the na- 



