240 REPORT ON THE TRANSACTIONS OF THE SOCIETY OF 



the influence of the atmospheric pressure on galvanic polarization; 

 by which he has found that this influence is inappreciable, and that 

 the polarization depends only on the disengagement of the gas in the 

 nascent state. New researches on the heat disengaged by the current, 

 when it produces an exterDal effect, have satisfied M. Soret of the 

 correctness of the results which he had previously obtained, but at 

 the same time he insists on the fact that, for an equal quantity of 

 chemical action, the external effect produced by a current is not 

 always proportional to the diminution of intensity, and he has given 

 a proof derived from the action of currents of induction. 



It remains for us to notice two communications of M. De la Rive, 

 the one relating to the electro-magnetic rotation of liquids, the other 

 to the propagation of electricity in gaseous mediums highly rarefied. 



On occasion of an investigation relative to the rotary action of 

 helices and magnets on liquids traversed by electric currents, M. 

 Bertin had contested the accuracy of an experiment made thirty-five 

 years ago by M. De la Rive, by means of which he had demonstrated 

 that when a magnet is hollow the rotation of the mercury placed 

 within it takes place in a contrary direction to that of the mercury 

 without, the two liquid conductors having the same level and being 

 equally traversed by a current radiating from the centre, or converging 

 towards the centre. M. De la Rive has resumed this experiment, 

 and has varied it by employing as well a hollow magnet of tempered 

 steel as a tube of soft iron magnetized either by an encircling helix 

 or by a strong electro-magnet. He has made use of tubes of different 

 dimensions, both of cast and wrought iron, and has verified the accu- 

 racy of his first assertion. A single case only occurred in which the 

 rotation took place in the same direction within and without, and that 

 was, when employing the hollow magnet of steel, the level of the 

 mercury both without and within was below the magnetic pole and 

 near the middle of the magnet — an exception which is referable 

 probably to the influence of the second magnetic pole. 



In his second experiment relating to the propagation of electricity 

 in gaseous mediums, greatly rarefied, M. De la Rive proceeded to the 

 consideration of the subject under two distinct points of view, namely, 

 the action of the magnet upon currents transmitted across such me- 

 diums, and the propagation of the currents with the phenomena 

 which accompany it — such, among others, as the stratification of the 

 electric light. He began with describing the effects obtained under 

 the former point of view, and particularly those relating to the rota- 

 tion of luminous currents in different planes and with different veloci- 

 ties, according to the conditions of the experiment — a rotation which 

 lie had already made known ten years ago. As to the second point, 

 he can be said as yet' scarcely to have approached it; yet he has been 

 able to conclude even from his first attempts, of which he will com- 

 municate the sequel at some future time, that the gaseous medium, 

 when traversed by electricity in motion, undergoes, conformably to 

 the ideas of M. Riess, mechanical and physical modifications consist- 

 ing essentially in alternations of condensation and dilatation. M. De 

 la Rive terminates his memoir by pointing out that his new researches 



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