ACTION OF WATEK ON IRON. 303 



he received the BibUotheque Universelle, published in February 

 last, containing an article by Professor Schoenbein on the very 

 subject. In this he shows^ as indeed he had previously done in a 

 letter to Dr. Faraday in the Lond. & Edinb. Philosophical Maga- 

 zine for December last, that he, Schoenbein, "had already demon- 

 strated, 1st. That iron only comports itself passively as the anode 

 in relation to the oxygen disengaged by the current in aqueous 

 solutions, which contain alone oxygenized compounds, as oxacids, 

 oxide, oxysalts, &c.; 2nd. That the state of chemical indifference 

 of iron can only be obtained with respect to oxygen ; and, 3rd. 

 That this metal acts in its ordinary way when it is plunged as an 

 anode into aqueous solutions of the hydracids of the chlorides, 

 bromides, iodides, fluorides, or sulphurets ; in fact, in solutions 

 of combinations whose negative element has a great affinity to 

 iron. In these cases the oxygen resulting from the electro- che- 

 mical decomposition of the water combines with the ix'on in the 

 same way as the chlorine or iodine disengaged under like cir- 

 cumstances. Hence," continues Schoenbein, " as the substances 

 which are in solution in sea water are for the most part electro- 

 lytes which do not contain oxygen as a constituent, it is impos- 

 sible, after the facts above stated, that iron as an anode can be 

 indifferent chemically, in relation to sea water; but, on the con- 

 trary, this metal must combine with the oxygen, chlorine, &c. 

 disengaged by the current." 



Scheenbein then states the result of an experiment he made 

 directly with sea water, by plunging an iron wire connected with 

 the positive pole of a pile into it, thereby closing the circuit ; no 

 oxygen was evolved at the iron, which was oxidized, in strict 

 accordance with his general principle. He then proceeds to 

 show, that assuming Mr. Hartley's view to be right, it involves 

 an initial absurdity or contradiction in principle ; and finally 

 concludes, that the observation of Mr. Hartley must be con- 

 sidered as doubly anomalous, namely, in relation to common 

 and acknowledged electro-chemical laws, and also to those spe- 

 cial ones developed by himself. 



126. The anomaly, however, may now be considered simply 

 as an error, but one of a very serious character, apparently from 

 the extent to which its consequences seem to have been wrought 

 out in the application stated to have been made of brass as pro- 

 tectors to all the work of the Liverpool Docks, which, unless 

 removed, must be attended with the rapid decay and destruc- 

 tion of all the iron it is connected with. I have also understood 

 that, acting on this presumptive protection, the Liverpool chain- 

 cable makers now supply gun-metal pins to their cable shackles, 

 at intervals of a few fathoins, by way and under the name of 



