14'1' Dr. C. F. Schoenbein on some 



whatever may be the degree of dihition of either fluid made 

 use of. As far as I know, chemists do not allow pure zinc 

 to be in the least chemically affected by an aqueous solution 

 of chemically pure potash, whilst copper is readily dissolved 

 by nitric acid. Now according to the views of De la Rive, 

 the copper wire in the arrangement before mentioned ought 

 to be positive with regard lo the zinc, which is immersed in 

 the alkaline fluid. The philosopher of Geneva has tried to 

 reconcile some similar facts disagreeing with this theory by 

 asserting, that the largest portion of electricities separated 

 from each other by the action of nitric acid upon some metal 

 reunites upon the surface of the latter, on account of the great 

 conductive force of the nitric acid (see the above-mentioned 

 Memoir, p. 39. )• But it appears to me that such an explica- 

 tion cannot be applied at all to the case in question, because 

 the alkaline solution and zinc of themselves (without making 

 part of a closed circuit) do not chemically act upon each other, 

 consequently cannot (according to the notions of De la Rive) 

 produce any current, and because that metal continues to be 

 positive to copper, though the acid into which the latter (the 

 copper) plunges be ever so much diluted with water, that is 

 to say, its conductive force ever so much diminished and 

 brought even below that of the alkaline solution. Before I 

 leave the subject in question, I cannot omit in a general way 

 to state that the result of my recent researches seem to 

 prove that the voltaic relation which any two metals bear 

 one to another within pure water is not changed at all, if the 

 latter substance be mixed in any proportion with sulphuric, 

 nitric, muriatic acid, potash, ammonia, &c. and that portions 

 of the same metal, though they are plunged into very dif- 

 ferent aqueous fluids and are very differently acted upon by the 

 latter, cannot assume opposite voltaic conditions. For in- 

 stance, if copper be negative to tin within water, these metals 

 continue to preserve that voltaic relation to one another 

 whether they be placed within acidulated water or within 

 aqueous ammonia. If copper be negative to lead within 

 water, this voltaic bearing is not changed by putting the 

 metals mentioned either into strong or into much diluted 

 nitric acid. If one piece of zinc be plunged into a solution of 

 potash, another in water mixed with sulphuric acid, muriatic 

 acid, &c., the two pieces of zinc do not give rise to any current. 

 I am well aware that these assertions are strongly at variance 

 with the results of Davy, De la Rive, and others, and indeed 

 also with what very simple experiments seem to show ; but I 

 am prepared to say that if the same two metals are sometimes 

 positive, sometimes negative with regard to each other, accord- 



