THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



APRIL 1867. 



XXXIII. O.i the Propagation of Electricity in highly Rarefied 

 Elastic Fluids, and in particular on the Stratifications of the 

 Elective Light in very rare media*. By Professor A. de la 



RlVEf. 



§ 1. General Considerations. 

 T was long supposed that whereas gases oppose a greater or 



i 



ess resistance to the passage of electricity, a vacuum con- 

 ducts it very well. The use of RuhmkorfFs induction-coil, by 

 supplying a better and more certain means of studying the pro- 

 pagation of electricity in rarefied gases, has shown that the pre- 

 sence in a space of the smallest quantity of ponderable matter 

 in the shape of an elastic fluid is sufficient to enable this propa- 

 gation to take place, but that an absolute vacuum prevents it 

 entirely. The demonstrative proof of this important principle is 

 due essentially to the conclusive experiments of Mr. Gassiot ; 

 although previously, if not completely admitted, it was at least 

 foreseen as an indirect consequence of earlier investigations J. 



* These researches form part of a more extended investigation into the 

 propagation of electricity by highly rarefied elastic fluids, which has ap- 

 peared in the Memoires de la Societe de Physique et d'Histoire Naturelle de 

 Geneve, vol. xvii. p. 59, and an abstract of which has been published in the 

 Comptes Rendus de VAcademie des Sciences de Paris for April 13, 1863. I 

 now publish them with some additions; and I shall also publish in an 

 early Number of the Archives another part of the same investigation, 

 which I have completed since the first publication, and which relates to the 

 action of magnetism on electric discharges which are traversing highly rare- 

 fied gaseous media. — A. de la Rive. 



t Translated from the Archives des Sciences Physiques et Naturelles, 

 vol. xxvi. p. 177 (July 1866). 



X See Traite de VElectricite, par A. de la Rive, vol. ii. p. 112. 

 Phil. Mag. S. 4 Vol. 33. Ts T o. 223. April 1867. R 



