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 LII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



Professor Faraday's Recent Discoveries. 



1 834. TJAPERS were read, entitled, " Experimental Researches 

 Feb. 13. — *- in Electricity. Sixth and Seventh Series." By Michael 

 Faraday, Esq., D.C.L., F.R.S., Fullerian Professor of Chemistry in 

 the Royal Institution. 



In the course of his experimental investigation of a general and 

 important law of electro-chemical action, which required the accurate 

 measurement of the gases evolved during the decomposition of water 

 and other substances, the author was led to the detection of a curious 

 effect, which had never been previously noticed, and of which the 

 knowledge, had he before possessed it, would have prevented many 

 of the errors and inconsistencies occurring in the conclusions he at 

 first deduced from his earlier experiments. The phaenomenon observed 

 was the gradual recombination of the elements which had been 

 previously separated from each other by voltaic action. This hap- 

 pened when, after water had been decomposed by voltaic electricity, 

 the mixed gases resulting from such decomposition were left in con- 

 tact with the platina wires or plates, which had acted as poles ; for 

 under these circumstances they gradually diminished in volume, water 

 was reproduced, and at last the whole of the gases disappeared. On 

 inquiring into the cause of this reunion of the elements of water, the 

 author found that it was occasioned principally by the action of the 

 piece of platina, which had served for the positive pole ; and also that 

 the same piece of platina would produce a similar effect on a mixture 

 of oxygen and hydrogen gases obtained by other and more ordinary 

 kinds of chemical action. By closer examination, it was ascertained 

 that the platina, which had been the negative pole, could produce the 

 same effect. Finally, it was found that the only condition requisite 

 for rendering the pieces of platina effective in this recombination of 

 oxygen and hydrogen, is their being perfectly clean, and that ordinary 

 mechanical processes of cleaning are quite sufficient for bringing them 

 into that condition, without the use of the battery. Plates of platina, 

 cleaned by means of a cork, with a little emery and water, or dilute 

 sulphuric acid, were rendered very active ; but they acquired the 

 greatest power when first heated in a strong solution of caustic alkali, 

 then dipped in water to wash off the alkali, next dipped in hot strong 

 oil of vitriol, and finally left for ten or fifteen minutes in distilled 

 water. Plates thus prepared, placed in tubes containing mixtures of 

 oxygen and hydrogen gases, determined the gradual combination of 

 their elements : the effect was at first slow, but became by degrees 

 more rapid j and heat was evolved to such a degree, indeed, as fre- 

 quently to give rise to ignition and explosion. 



The author regards this phenomenon as of the same kind as that 



discovered by Davy in the glowing platina ; that observed by Dobe- 



reiner in spongy platina, acting on a jet of hydrogen ,uas in atmo- 



ipheric air; and those BO well experimented on by MM. Dulong and 



2 1' '_' 



