[ 175 ] 



Note from Professor Faraday to Mr, Richard Taylor on the 

 preceding Paper. 



Dear Sir, 



¥ AM mucli obliged to you for a sight of M. Schoenbein's 

 * paper, the experiments and observations in which are ex- 

 cellent. The cause of the phaenomena he has so well distin- 

 guished is indeed exceedingly difficult to be distinguished 

 at present, and I was in hopes that the doubt on my mind 

 when I ventured the view referred to would be evident from 

 my words, " My strong impression is," &c.* Moreover, 

 M. Schoenbein, and also M. Alb. Mousson in an attempt 

 which he has made to explain the cause t, have not given 

 my view clearly. I have said, that my impression is, that 

 the surface of the metal is oxidized, or else that the supe?-^ 

 Jicial particles of the metal are in such relation to the oxygen 

 of the electrolyte as to be equivalent to an oxidation J; mean- 

 ing by that, not an actual oxidation, but a relation Hke that of 

 the particles of amalgamated zinc to the oxygen of the water 

 in dilute sulphuric acid before the electric current which 

 tends to be formed is established. (See Experimental Re- 

 searches, Eighth Series, par. 949.) 



The state seems to me to be one of a very delicate equili- 

 brium of forces, though of course that condition of things 

 which can produce it can also retain it; and this notion seems 

 to be confirmed by the intermitting action originally mentioned 

 by Herschel. I quite agree with M. Schoenbein's conclusion, 

 " that Faraday's views concerning the passive state of the 

 iron do not explain it satisfactorily," and I only regret that 

 the other views which have been put forth are, as far as I 

 can perceive, not more satisfactory. For instance, that by 

 M. Mousson leaves out of view the capital and leading fad, that 

 apiece of iron in the peculiar state may remain for six months 

 (as I know by experiment) in nitric acid of sp. gr. 1*35 with- 

 out being in the least affected, although no platina or primary 

 metal is in contact wiih it. 



I was somewhat struck the other day, whilst readii.g in your 

 useful ' Scientific Memoirs' M. Nobili's paper on a new chro- 

 matic scale, on finding that he accounts for the colours of his 

 thin plates by assuming films of oxygen and acid || ; which he 

 considers asadhering permanently to thesurfaces of the platina, 

 iron, and steel plates which he used in his experiments, without 



* Lond. and Edinb. Phil. Mag., vol ix. July 1836, p. 61. 

 t Lihliotheqite Universetlc dc Geneve^ Sept. 1 836, p. 1 65. 

 X Lond. and Edinb. Phil. Mag., vol. ix. July 1836, p. 61. 

 jl Scient. Mem , Part 1. p. 108 



