Cobalt and Nickel incapable of being rendered, inactive. 54-7 



The Biblioth. Univers. also alludes to a paper read at 

 Liverpool by Mr. Hartley, on the Preservation of Iron against 

 the action of sea water. The fact stated by that gentleman is 

 on account of its anomaly highly interesting, and seems to 

 enter into that class of electro-chemical phenomena which 

 have been the subject of my researches these last two years. 

 If you recollect a statement of mine made in a paper " On a 

 peculiar Action of Iron," &c.,* you will be aware that the re- 

 sult obtained from Mr. Hartley's experiments does not quite 

 agree with what I have found out to be a general fact. The 

 statement alluded to runs as follows: In solutions containing, 

 besides oxy electrolytes, others of a different nature, for instance, 

 hydracids, haloid salts, &c, no evolution of oxygen takes 

 place (at the iron being the positive electrode of the pile) in 

 whatever manner the circuit may be closed. Now if in Mr. 

 Hartley's voltaic arrangement brass is to iron (in an electrical 

 point of view) what platinum is to the latter or any other 

 readily oxidable metal, according to my experiments we 

 should suppose that iron, being voltaically associated with 

 brass, would be chemically acted upon by sea water, that is to 

 say, be oxidized and chloridized. You may easily ascertain 

 the correctness of my statement by plunging an iron wire 

 which is connected with the positive pole of a pile into an 

 aqueous solution of chloride of sodium, closing thereby the cir- 

 cuit. You will observe that the iron is not turned inactive, but 

 corroded, and effects are produced quite consonant to the well 

 known electro-chemical laws. I made a couple of days ago 

 some experiments with sea-water itself, and I found that iron 

 was attacked by it when a current passed from the metal into 

 the fluid. As you can easily imagine, the disagreement of 

 Mr. Hartley's observations with mine, makes me exceedingly 

 desirous of becoming acquainted as soon as possible with the 

 particulars of that gentleman's researches. I hope the next 

 number of the Philosophical Magazine will satisfy my curiosity 

 on this point.f 



Last summer, during a short stay at Stuttgard, I made in the 

 laboratory of Professor Degen there, and in company with this 

 able chemist, some experiments upon cobalt and nickel, to as- 

 certain whether these metallic bodies are capable of being 

 rendered inactive. Having but a very small quantity of these 

 metals at our disposal, we were obliged to limit the number 

 of our experiments to a very few, and to execute them on 



* Lond. and Edinb. Phil. Mag., vol. x. p. 267. 



t We are not aware that any further statement of Mr. Hartley's results 

 has yet appeared : that given in page 554 of the present Number is sub- 

 stantially the same with the notice cited above.— Edit. 



4 A2 



