THE 



LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



♦ 



[FIFTH SERIES.] 



OCTOBER 1885. 



XXXIV. On the Electric Conductivity of Gases. 

 By F. Stenger*. 



[Plate IX.] 



THE present research has two objects. In the first part, 

 the author endeavours to show, partly by use of the 

 unusually rich literature of the subject, and partly from his 

 own researches, that there exists no distinction universally 

 applicable between the arc-discharge and the glow-discharge. 

 Upon what factor the appearance of the one or other of the 

 two forms depends, and under what experimental conditions 

 the two forms of discharge can pass into each other, will form 

 the subject of the second part. 



Part I. 



I may be allowed, in the first place, briefly to place together 

 the essential characters of the arc-discharge as distinguished 

 from the glow-discharge ; and for this purpose I confine 

 myself entirely to the normal form of discharge. 



(1) The gas-stratum in the arc-discharge possesses a much 

 smaller resistance than in the glow-discharge. 



(2) In the arc-light the anode is more strongly heated 

 than the kathode, whereas in the glow-light the reverse is 

 the case. 



(3) In the spectrum of the arc-light, the light due to the 

 substance of the electrodes overpowers that of the stratum of 

 gas between them ; while, on the other hand, in the glow-dis- 



* Translated from Wiedemann's Annalen, No. 5 (1885). 

 Phil. Mag. S. 5. Vol. 20. No. 125. Oct. 1885. Z 



