Prof. Schoenbein on Current Electricity, 311 



The experiments by which the latter part of this law has been 

 established are contained in a paper which will shortly be 

 presented to the Royal Irish Academy. 



In reference to the peculiar state of the metal in nitric acid, 

 after it is separated from the voltaic influence, it may be use- 

 ful to remark, that the more completely it is developed and 

 the more perfectly inactive the metal becomes, the brighter is 

 the surface which it presents to the liquid ; and as Faraday has 

 shown that the remarkable properties of a platina plate, when 

 polarized by acting as the positive pole of a battery, depend 

 upon the absolute cleanness and purity of its surface, is it 

 not probable that, in like manner, the inactive states of these 

 metals depend upon the pure metallic surfaces which the 

 voltaic action develops by dissolving away every trace of oxide, 

 upon which surface, when thus more perfectly freed from all 

 impurity than can be effected by mechanical means, the acid 

 has either no action or a greatly diminished action ? This is 

 merely however stated as a simple conjecture, and I can offer 

 no explanation of most of the particular facts which have been 

 described. I am. Gentlemen, yours, &c. 



Belfast, Feb. 6, 1838. Thomas Andrews. 



XL VI I. Further Experiments on the Current Electricity ex^ 

 cited by Chemical Tendencies, independent of ordinary Che- 

 mical Action, By Professor Schcenbein. 



To the Editors of the Philosophical Magazine and Journal, 

 Gentlemen, 

 tiJJOME time ago I communicated to Dr. Faraday a letter, in 

 ^ which the results of my late researches on the voltaic re- 

 lations of some metallic peroxides, inactive iron, and platina 

 were made known to that distinguished philosopher. As I un- 

 derstand that my letter has been, or is about to be published 

 in your valuable Journal*, you will perhaps be kind enough 

 to give a place also to this paper in one of the next Numbers 

 of the Magazine. 



After having ascertained that the peroxides of silver and 

 lead, as well as inactive iron and platina, being voltaically 

 associated with one another, are capable of exciting current 

 electricity quite independent of what is commonly called 

 " chemical action," I extended my experiments to a series of 

 other substances, which, according to the assertion of all che- 

 mists, do also not chemically act upon each other, for in- 



* Prof. Schoenbein*s letter to Mr. Faraday here alluded to appeared in 

 our last Number, p. 225. 



