Inactivity of Bismuth and Iron. 545 



the oxygen 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 very same circumstances, it does not seem to 

 undergo any change whatever, for it is violently acted upon by 

 nitric acid (of sp. gr. 1-4) and unites with the oxygen resulting 

 from the electro-chemical decomposition of water or any other 

 oxyelectrolyte. It is particularly the last-mentioned difference 

 of bearing between the two metals which makes me suspect that 

 the peculiar condition of iron is not produced by the same 

 cause which occasions the inactivity of bismuth, that is to say, 

 that the latter effect is not brought about by a current passing 

 in a certain direction through bismuth. There is another fact 

 which seems to speak in favour of this opinion : according to 

 my experiments, peroxide of lead proves to be the most power- 

 ful of all substances which are capable of turning common iron 

 into its peculiar state. Peroxide of lead, in whatever manner I 

 tried to combine it with bismuth, did not appear to have any 

 action upon the metal, for this substance was dissolved by ni- 

 tric acid just in the same way as it was when put into the said 

 fluid without any voltaic association. Now it is to be asked, 

 in what manner does platinum weaken the chemical action of 

 nitric acid upon bismuth? Are we to believe that in the case 

 in question the former acts in a quite peculiar way, that it puts 

 into play an agency of a nature as yet unknown and entirely 

 different from current electricity ? I am certainly not much 

 inclined to draw any such inference from the fact alluded to, 

 but at the same time 1 must confess, that for the present, at 

 least, I am not able at all to account for the anomaly spoken 

 of. Before passing from the subject of the peculiar condition of 

 bismuth to another one, allow me to mention to you some more 

 phenomena which bear upon the same matter, and which have, 

 perhaps, not yet been observed by Mr. Andrews. After (by 

 the agency of platinum) the violent action of nitric acid (sp. gr. 

 1*4) upon bismuth has been changed into a slow one, and both 

 metals brought out of contact, bismuth loses its metallic lustre 

 and assumes a blackish appearance ; after a short time, how- 

 ever, the metal turns bright again by itself, and remains so 

 until it is touched a second time by platinum. As long as the 

 contact between both metals is maintained, certainly there 

 is no change of the surface of bismuth to be observed, but no 

 sooner have they ceased to touch each other than the bismuth 

 begins to blacken again ; it reassumes, however, after some 

 lapse of time, its former lustre. This change of surface can 

 Third Series. Vol. 1 1. No. 70. Dec. 1837." 4 A 



