Two Fluids, and of Two Metals not in Contact. 549 



cuits composed of acid, iodide of potassium, amalgamated and 

 non-amalgamated zinc. 



As evident from the Table^ the current has In these circuits^ 

 on employing pure sulphuric acid or hydrochloric acid in the 

 diluted state, after a first deflexion in the direction s<i, the 

 direction s> i with great energy, or the acid the ascendency 

 over the iodide of potassium. The same is the case, and indeed 

 without the first deflexion 5 < i, when sulphuric acid containing 

 nitric acid or 2yure concentrated hydrochloric acid (spec. gr. 

 1 '138) is employed. — In all these cases, therefore, the non-amal- 

 gamated zinc acts as a negative metal, for instance like silver, 

 towards the amalgamated; and yet it is always attacked far more 

 energetically than the latter ; by the concentrated hydrochloric 

 acid, indeed, with a truly stormy violence. How can this be 

 explained in a satisfactory manner according to the chemical 

 theory ? 



I say in a satisfactory manner ; for the explanation which 

 Faraday has given of the cause of the positiveness or greater 

 activity of the amalgamated zinc in comparison with the un- 

 amalgamated, — namely, that the latter, being directly attacked 

 by the acids, neutralizes them by the oxide it produces, and 

 thus retards the progress of oxidation, whilst at the surface of 

 the amalgamated zinc the oxide formed is instantly removed by 

 the free acid present, and the clean metallic surface is always 

 ready to act with full energy upon the water*, — can scarcely be 

 termed satisfactory, as it is in open contradiction to experience, 

 which shows that under like circumstances by far more of the 

 unamalgamated than of the amalgamated zinc is dissolved. 



Just as little can the doctrine of local and circulating chemi- 

 cal forces, and the assumption that the latter are produced in 

 greater energy or quantity by the amalgamated zinc than by the 

 unamalgamatedt, be admitted here, or generally, as vahd. This 

 doctrine possesses, it is true, such pliancy, that by it all the nu- 

 merous cases, where, as in the experiment of Berzelius (p. 486.), 

 the negative metal is more violently attacked than the positive' 

 may be set aside, with the explanation that it is effected by a 

 local action which adds nothing to the current ; but, on a closer 

 view, it is nothing more than a gratuitous hypothesis, which 

 the chemical theory finds itself compelled to adopt in order 

 not most palpably to fall into a contradiction with the fact, that 

 the energy of the electromotive force no ways corresponds to 

 the violence of the attack on the zinc or positive metal. Where 

 is there any proof of this? It is as much in want of one, as 



* Exp. Res. § 1005. f Exp. Res. f§ 947, 99Q, 1120, 



