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.

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    liberty to give you a short account of the results obtained from them. It certainly cannot be denied, that there exists some analogy between the peculiar condition of Iron and that of Bismuth but my impression at present is, that there is only a similarit}' and not an identity of cases. This opinion is founded upon the following facts. The chemical action of Iron upon nitric acid can, as it is now well known, be entirely stopped b}' a variet}' of ways, whilst according to my experiments it is impossible to obtain such a result with Bismuth. I voltaically associated this metal with all the substances known to be capable of rendering Iron completely inactive but by so doing I could never succeed so far as to prevent Bismuth from being chemically acted upon b)' nitric acid. It is true, by putting in contact the metallic body in question with Platinum the chemical action of nitric acid spec. gr. 1.4 may be reduced to such a low degree of intensity, that no visible disengagement of binoxide of nitrogen takes place and the piece of Bismuth (immersed in nitric acid) assumes a bright appearance. But the oxidable metal being in this state is nevertheless uninterruptedly attacked by the acid fluid, as it can be easily shown by having recourse to the galvanometer. There are besides some other facts, which put the continuance of chemical action in the circumstances mentioned beyond any doubts. I think I have first ascertained the remarkable fact, that Iron can be rendered thoroughly inactive not only towards the oxigen of nitric acid (of an}' degree of dilution) but also to the oxigen disengaged (by the action of a voltaic current) out of aqueous solutions of any oxidized body or any oxyelectrolyte. You know, that such a state of Iron is called forth by making- this metal act the part of the positive electrode of a pile and closing the circuit in a certain manner. Now if Bismuth be placed in these ver}' same circumstances, it does not seem to undergo any change whatever, for it is violently acted upon by nitric acid (of spec. gr. 1.4) and unites with the oxigen resulting from the electro-chemical decomposition of water or any other