The letters of Faraday and Schoenbein, 1836-1862 : with notes, comments and references to contemporary letters / edited by Georg W.A. Kahlbaum and Francis V. Darbishire.

Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: The letters of Faraday and Schoenbein, 1836-1862 : with notes, comments and references to contemporary letters / edited by Georg W.A. Kahlbaum and Francis V. Darbishire. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    39/404 (page 19)
    Now why does F in the first case not become inactive by the current produced by its l^eing plunged into B? It seems to be an indispensable condition for calling forth the inactive state in iron, that in the moment of its being immersed into the acid a current of a certain energy is passing through it. The current produced by the part of the metal immersed is of sufficient strength, when both ends of the iron wire plunge into the acid contained in only one (small) vessel; but when this same current has to pass through the acid of two vessels and besides to enter and issue into and from the connecting platina wire, its strength is diminished below the degree necessary for producing the effect in question. But if this way of accounting for the fact be correct, it is to [be] asked, how it comes, that with a connecting wire, whose ends are attacked by the acid of the vessels different results are obtained. It is obvious, that in the second case, two currents moving in opposite directions and originating in C and D are established, as soon as the iron wire EF has connected the v^essels A and B. Besides these currents a third one is produced by the immersion of F in B. But this current having to make the same way, which the current in the first case must pass, why is its effect different from what that of the latter is? Now it seems to me, that if two currents of opposite direction circulate through our circuit of the second case, they remove in some way or other the obstacles, which the third current (in itself of weak power) would have to overcome, if it was moving alone through the circuit; or in other terms if two opposite currents cross the nitric acid, its conducting power for a third current is increased. In the third case, there arc likewise two opposite currents established, as soon as F dips m B; one produced by C the other by E; and there is again a current excited by F, which must be considered as the cause of the peculiar state of this end. It is only to be wondered at, why D when having been made inactive by immersion in strong nitric acid or by the help of platina, is