252 Mr. J. Prideaux on the Theory of Voltaic Action. 



nected through a wire, — have their contents gradually altered 

 by transference of the acid into the alkali, and vice versa, until 

 either neutralization has taken place, or the activity of the cir- 

 cuit is so tar lowered as to have no longer power to commu- 

 nicate the requisite impetus. Oxygen goes to the zinc, and 

 hydrogen to the copper, in most cases; and we have seen (22) 

 that not only this took place, but that the alkali continued to rise, 

 and the acid to descend, in opposition to their specific gravity. 

 28. It is seen (23) that addition to the quantity of copper 

 augments the effect ; but I do not find this happen unless the 

 additional copper be in immediate liquid communication with 

 the zinc. 



a) A 3-inch zinc plate was set in a water-tight copper case 

 (open at top), with due precautions against contact: the case 

 was nearly filled with diluted nitric acid (1*60), and placed in 

 a vessel of the same liquid, which just reached its upper edge. 

 The case and zinc being both furnished with conducting wires, 

 were put in communication with the magnetest ; 



Deflection .... 40° 



b) An additional copper case, open at both ends, was then 

 placed about the first, clear of contact, and also made to com- 

 municate with the same mercury box as the first case. 



No increase of deflection. 



c) A little more of the same acid was then poured on, to 

 overflow the whole, and establish immediate liquid communi- 

 cation between the zinc and the external copper. As soon as 

 it ran over the edges, 



Deflection .... 42° 



The conducting medium is the same in (b) as in (c) ; but the 

 transference of particles from the zinc to the external copper 

 is intercepted in (b\ and no other evident difference appears. 

 The communication in (c) being only over the edge of the inner 

 case, the increase is proportionally small ; 40° to 42°, or 38 to 

 43 current. 



Thus we may imagine the copper exalting, by contact or by 

 metallic communication, the positive character of the zinc; the 

 zinc thus exalted decomposing the water with peculiar viva- 

 city, attracting the negative oxygen, charging and repelling 

 the positive hydrogen; the latter being at the same time at- 

 tracted, and oxygen charged and repelled by the copper: — 

 oxygen thus continually travelling from copper to zinc; hy- 

 drogen from zinc to copper ; and each discharging its excess 

 of electricity as it arrives. This attraction and repulsion being 

 of course stronger, and the motion of the charged panicles 

 consequently quicker, the less the interval between the plates ; 



