Dr. Schoenbein on the peculiar Voltaic Condition of Iron. 267 



damp — showers; and until today (25th) the weather has been 

 very stormy, with heavy wind, rain, and hail. 

 Sidmouth, February 25, 1837. 



P.S. In the Magazine for last month, (January,) p. 75, 

 Mr. Mallet has mentioned the occurrence of an aurora on the 

 evening of October 5th, 1836. May I be allowed to state, that 

 at about 7 o'clock on that night I observed, at Sidmouth, a 

 patch of faint pink light partly over U. Major, but there was 

 no further appearance of aurora here? 



LIV. Experimental Researches on a peculiar Action of Iron 

 upon Solutions of some Metallic Salts. By Dr. C. F. Schcen- 



BEIN.* 



COME time ago I published several papers f, in which I 

 ^ made known some very remarkable facts regarding the 

 action of iron upon oxygen. According to the notions ge- 

 nerally adopted by philosophers respecting the action of metals 

 performing the function of the positive electrode upon oxy- 

 gen set free by voltaic action, iron, as one of the more readily 

 oxidable metals, chemically combines with that element. In 

 one of the papers alluded to, I have shown that these notions 

 with regard to iron do not hold good in all cases, and that 

 this metal acquires under certain circumstances the property 

 of platina or gold, that is to say, that whilst constituting the 

 positive electrode, it is neither oxidized nor otherwise cliemi- 

 cally affected by oxyacid solutions, which usually act upon 

 iron with more or less violence. 1 have further observed, that 

 this inactivity of iron depends upon the manner of closing the 

 circuit, as well as upon the chemical nature of the electrolytes 

 contained in the solutions in which the polar wires of the 

 pile are immersed. Solutions containing oxyelectrolytes which 

 act chemically upon iron, as, for instance, sulphuric or nitric 

 acid, require the circuit to be closed in a certain manner in 

 order to evolve ox^^gen at the positive iron. Solutions con- 

 taining oxyelectrolytes which do not sensibly act upon iron, 

 as, for instance, those of potash, soda, and a great many oxy- 

 salts, allow the evolution of oxygen at the positive iron quite 

 independently of the manner of closing the circuit. In solu- 

 tions containing, besides oxyelectrolytes, others of a different 

 nature, for instance, hydracids, haloid salts, &c., no evolution 

 of oxygen takes place in whatever manner the circuit may be 

 closed. From these facts, and others stated elsewhere, I am 



* Communicated by the Author, through Mr. Faraday. 

 t See Lond. and Edinb. Phil Mag., vol. ix. pp. 53, 122, 259; and present 

 volume, p. 133, 172. — Edit. 



2 M 2 



