486 M. PoggendorfF on Galvanic Circuits composed of 



It can no longer, therefore, be a question whether there is a 

 true spark on junction without metalHc contact ; moreover, 

 other good reasons render very improbable the existence of the 

 high tension requisite in the still open simple circuit*. 



The electrolytic law is otherwise circumstancedo The cor- 

 rectness of this important law, with which Faraday has en- 

 riched the science of electricity, can be subject to no doubt; 

 but many well-founded objections may be raised against its inter- 

 pretation in favour of the chemical theory. The law consists 

 in the fact that the quantities of the bodies decomposed in the 

 single cells of the voltaic battery are in proportion to the che- 

 mical equivalents. It proves that the passage of like quantities 

 of electricity is necessary for the decomposition of equivalent 

 masses, but nothing more. It takes no part in the question 

 respecting the origin of galvanic electricity. It is equally 

 correct, whether the voltaic ciu-rent originate from the contact 

 of the metals, or from the chemical action on the zinc, or from 

 any other cause f. 



A proof in favour of the one or the other origin might 

 perhaps be drawn from it, were it exclusively peculiar to the 

 voltaic current, which would at the same time estabhsh quite 

 an essential distinction between voltaic electricity and magnetic, 

 thermal, frictional, and animal electricity. But if, on the other 

 hand, it is no pecuharity of the voltaic electricity, if it is rather 



* [At the time when the sheets of the German original were sent to press, Prof. 

 PoggendorfF had not seen the collective edition of the Experimental Researches, 

 in the preface to which Mr. Faraday acknowledges himself to have been in 

 error with respect to the production of the spark without contact. — W. F.] 



t The error with respect to using this law as an argument has originated 

 from presupposing what first ought to have been proved by it, that the excita- 

 tion of the electricity was effected by the solution of the zinc ; while in reality, 

 this solution, when amalgamated zinc and dilute sulphuric acid are employed, 

 is solely the effect, the product of the electric current, and, when common zinc 

 is used, arises partly from this current and in part from a pure chemical process 

 entirely foreign to the circuit. It has happened with this law as with the well- 

 known fact that in general the easily oxidable metals are the more positive. 

 A connexion between oxidability and positiveness is accordingly evident,but 

 which of these is causal, this or that, remains totally undecided. That it is, 

 nevertheless, still continued to be interpreted in favour of the chemical theory, is 

 the less justifiable, as several cases are known (and may every moment be 

 increased by new ones) where the negative metal, notwithstanding that it is 

 actually much more powerfully acted upon by acids than the positive one, still 

 remains negative towards this. We need only call to mind the old experiment 

 of Berzelius {Gilb. Annalen, vol. xxxv. p. 27), which, it is true, De la Rive 

 conceives he has refuted, but which has long since been satisfactorily confirmed 

 by Ohm. Moreover, the fact observed by Ritter, Davy, and many others, and 

 which I have recently confirmed, that amalgamated zinc, notwithstandingif is 

 little or not at all attacked by dilute acids, is in these considerably positive 

 towards the so easily soluble unamalgamated zinc, deserves to b? rescued from 

 oblivion. 



