1814,] On the Fhjpolheses of Galvanism. 91 



cla'^sesof bodies he afterwards attempted to substantiate by more 

 direct experiments, in whicn the electrometer indicated the negative 

 electricity after being in ccnitact with acids, and the positive after 

 bein? in contact with alkalies. 



Two distinct sets of facts and experiments are here brought into 

 view those regarding the decomposition and transfer ot acids and 

 alkalies by the two iKtremitics of the pile, and those to whiclr the 

 electrometer was appUed : it is to the former of these only that the 

 present question has any reference. Before we can form a correct 

 (udLmieiu concerning them, it will be necessary to attend a little 

 more minutely than has hitherto been done to the electrical state ot 

 the water in the interrupted circuit. When water, or any other 

 conductor, is interposed between two substances that are m ditterent 

 states of electricity, its first effect is to form a communication be- 

 tween them, by means of which their electricities are equalized, 

 the water itself, as well as the two electrified bodies, all acquiring 

 the «ame degree of electricity. When the two extremities of the 

 pile are connected by the intervention of water, there is, in the hrst 

 instance, an attempt to produce this equilibrium ; but tiie equih- 

 brium is no sooner formed than it is again destroyed by the conti- 

 nual generation or evolution of electricity which goes on in the , 

 body of the pile. On this account the wire which was originally 

 positive is kept in that state, and the same with respect to the nega- 

 tive wire. But the two wires being immersed in water must have a 

 constant tendency to bring the water into the same electiical state 

 with themselves, and must, to a certain degree, accompash it; so 

 that we may conclude, that the water contiguous to the positive 

 wire is itself positive, and that contiguous to the negative wire 

 negative. These two portions of water must, however, be conti- 

 nuailv tending to equalize their electrical states with that oi the 

 remaining part of the water, and the result will be, tliat contiguous 

 to the two wires there are two portions of water, in the same, or 

 nearly the same, electrical states with the wires themselv-es, and 

 that the electricity diminishes in the successive portions of water, 

 until at lencth, iii the middle of the vessel, the fluid is in a neutral 

 state No\v if we dissolve a quantity of a neutral salt in this water, 

 we find that the acid particles diffuse themselves thror.gh the water 

 which is positively clcctriHcd, and the alkaline particles through 

 that which is negatively electrified. This is well illustrated in the 

 exi)eriments of Sir H. Davy, wheie the water was tinged with 

 litmus and turmeric ; for it was found that tlie intensity of the 

 effect produced on the colours, and consequently the quantity ot 

 acid and alkali contained in the water, was greatest near the wires, 

 and diminished until it arrived at the centre, whne the el.eet 

 ceased The transfer of the acid to the neighbourhood ot tlie 

 positive wire may, therefore, with greater prol)ability, be ascribed 

 to its being attracted by the positively electrified water, than to the 

 ix).itive wire itself; for it docs not attach itself immediately to the 

 «iie, but it dilVubCs itself through the water, in proporiion to the 



