550 M. Poggendorff ow certain Galvanic Circuits. 



the hypothesis imagined by De la Rive to get rid of the same 

 difficulty, viz., that the electricities separated by the chemical 

 process find a partial reunion at the very place where they are 

 developed, and consequently the intensity of the current need 

 not necessarily stand in direct proportion to the energy of this 

 process, — an hypothesis which has already been dissected by 

 Fechner*, and, in my opinion, founders even upon this ground 

 alone, that, cateris paribus, the current is the more intense the 

 better the fluid conducts, i. e. the easier this reunion can take 

 place in it. 



It is certainly an advantage of the contact-theory that it needs 

 neither the one nor the other hypothesis, but is perfectly satis- 

 fied with the simple view, that the so-(; ailed local action, that 

 which happens even previously to the closing of the circuit, is 

 a pure chemical process not at all appertaining to the circuit : 

 but the advantage were but slight, if it could merely enumerate 

 in its favour the simplicity of this view; its real superiority over 

 the chemical theories it acquires from its being a view well 

 founded on facts. All cases more accurately examined, whether 

 it be in the present Memoir or in previous ones by Fechnerf 

 and others, jirove in the most evident manner that the energy 

 of the direct chemical attack of the fluid on the positive metal 

 does in no way stand in any connexion with the intensity of the 

 excited electromotive force. And on the other hand it is not 

 proved that the local action is ever converted into circulating, or 

 weakened by it J. What has been advanced as such, is evidently 

 founded on error. The decrease of the hydrogen at the zinc 

 which results on the closing of the circuit, does not happen 

 from a transfer of tJiis hydrogen to the negative metal, but 

 simply from the oxygen being carried by the current to the 

 zinc, and there combining with the hydrogen. I hope shortly 

 to be able to confirm this by facts. 



The following note has been communicated by M. Poggen- 

 dorff to the Translator, with a request that it should be added : 



As I did not foresee on penning this memoir that it would have the honour of 

 being translated into English, it may he necessary to observe that I had not the 

 intention of bringing forward a complete refutation of the chemical theory of 

 galvanism, but merely to show that two facts recently brought forward in favour 

 of this theory do not prove what it is intended they should. For the same rea- 

 son many things have been passed over, or but briefly noticed, which appeared 

 unnecessary for Germany, but which needed a more detailed exposition for the 

 English readers, who in general are unacquainted with the researches of Ohm 

 and Fechner. Among others, might here be enumerated the distinction between 

 electromotive force and intensity of current, the not taking which into considera- 



* PoggendorfT's Annalen, vol. xlv. p. 232. 



f For instance, Poggendorff's Annalen, vol. xliii. p. 433. 



X Exp. Researches, § 996. 



