290 Mr. Grove o;» a new Voltaic Battery, afid 



the negative metal, and a powerful opposed force created; in 

 the constant combination copper is precipitated, and the op- 

 position is lessened ; in this there is no precipitation, and 

 consequently no counteraction. There is still, however, an- 

 other imaginary voltaic circle (I am tired of iterating the 

 word combination), which would be superior to any of these: 

 it is one of three elements; two metals, or substances having 

 the electrical properties of the metals, and an electrolyte ; of 

 these two substances, the positive should be analogous to zinc, 

 but the negative should possess a strong affinity for the cation 

 of the electrolyte, and unite energetically with it, as it sepa- 

 rates in a nascent state, or rather should of itself be able to 

 tear it from its associated anion; such a substance is, I think 

 I may say, at present unknown : the nearest illustration I can 

 give is mercury when associated with zinc and a cuperous 

 solution ; the peroxide of lead of Professor Schoenbein with 

 zinc and an electrolyte may serve as another. In a circuit of 

 this description we should have actually the sum of affinities 

 instead of their difference, and I can conceive no more power- 

 ful hydro-electric arrangement. 



To return to what is practicable. In my paper of the 15th 

 of April, I named three combinations, differing only in the 

 solution on the side of the zinc ; the three then mentioned 

 were muriatic acid, sulphuric acid, and caustic potash. I have 

 since that tried a variety of solutions on the zinc side, but on 

 the platina side only two new ones, viz. chloric acid and nitro- 

 sulphuric. The first of course was tried merely as a confirma- 

 tion of the theory, its application being obviously impracti- 

 cable: the electric effects produced by it differ little from 

 those of nitric acid. 



Nitro- sulphuric acid acts as an electrolyte much as nitric 

 acid, i. e. yields oxygen at the anode, and no hydrogen at the 

 cathode ; it is consequently equally applicable with nitric acid, 

 and more ceconomical. On the side of the zinc I have among 

 others, tried the following, which I give in the order of their 

 superiority. Acids: hydrofluoric, hydrochloric, sulphuric, 

 phosphoric. — Alkalies : potass and soda : Salts, chloride of 

 sodium, nitrate of potass, chlorate of potass, iodide of potas- 

 sium. — Spring water, rain water, distilled water. Of these 

 the second and third are the only useful ones, as wherever 

 salts are formed the diaphragm is sooner or later disaggre- 

 gated. 



If the operation of the battery be watched, the nitric acid, 

 as we should expect, changes colour, assuming first a yellow, 

 then a green, then a blue colour, and lastly becomes aqueous ; 

 after some time, nitrous gas, and ultimately hydrogen, are 



