548 M. Poggendorff on Galvanic Circuits composed of 



bottom of a cylinder which contained the platina and nitric 

 acid, and was surrounded by a wider one which received the 

 zinc and sulphuric acid. 



To be perfectly certain that the mixed acids did not develops 

 greater electromotive force than the separated, I caused them 

 to oppose one another by substituting in the apparatus just 

 described an acid mixture for the iodide of potassium. The 

 experiment was in other respects similar to the previous one, 

 only that the acids had a somewhat dilFerent degree of concen- 

 tration. Both diluted acids consisted of 1 part by weight of 

 concentrated acid, and 3 parts by weight of water, and equal 

 parts by weight of them were mixed on the one side of the 

 circuit with each other, and separated on the other side by 

 bladder. The experiment was made both with amalgamated 

 and non-amalgamated zinc, and previously heated platina. 



In both cases the result was, that the separated acids not only 

 excite an electromotive force quite as great as the mixed, but 

 have indeed a slight supe7'iority over these ! The latter fact is 

 the more remarkable, as the zinc plate (even amalgamated), im- 

 mersed in the sulphuric acid containing nitric acid, is evidently 

 more strongly attacked than that in the pure acid, and yet, after 

 washing both in water, is in this fluid negative towards the 

 latter plate. 



I consider these facts, indeed, as more demonstrative than 

 those already mentioned at p. 541, with the hydrochloric acid; 

 nay, as so decisive, that I regard the proofs against the tenabi- 

 lity of the argument, derived from Faraday^s experiment, in fa- 

 vour of the chemical theory of galvanism, as perfectly destroyed 

 by them*. 



However I cannot refrain from drawing attention to the cir- 



* The above fact is certainly decisive against the Favadayan theory, whicli 

 merely admits the chemical attack on metals as the cause of the voltaic electricity. 

 On the other hand, according to the theory of Becquerel or De la Rive, one 

 might deduce this near equality in the action of the separated and mixed acid 

 from an accidental compensation with the current originating from the contact 

 of both acids. Now fluids excite, it is true, an electric current by their reci- 

 procal contact, as was first actuaUy proved by Fechuer (Poggendorff's Annalen, 

 xlviii. pp. 1. and 225.). A portion of the action may therefore in effect have 

 originated from this cause ; but since the currents, which truly originate from 

 the reciprocal contact of the fluids, are always weak only, it is not probable 

 that this portion was considerable, and exercised any great influence on the 

 main result. As already mentioned, the separated acids have the superiority 

 over the mixed when the platina is inserted in the nitric acid ; the reverse 

 happens when the xinc is immersed in the nitric acid. But in both cases the 

 superiority is only slight. This appears to me to prove, that the current from 

 the fluids which in both cases must possess opposite direction, has no consider- 

 able part in the main action. 



