528 Action of the Electric Discharge on Gases and Vapours. 



place. The phenomenon seems to be a heat-dissociation pure 

 and simple. There is deposited on both the poles, not the 

 black conducting modification of carbon as in the case of 

 marsh-gas &c, but a grey nonconducting matter around 

 which the discharge leaps as it passes from wire to wire. 



The appearance of the same character and quantity of 

 deposit on each of the poles is, to my mind, conclusive 

 evidence that we have to do here, not with an electrolysis, but 

 with a heat-dissociation alone. I should make it a cardinal 

 requirement for a phenomenon of this kind that the deposits 

 on the poles be symmetrical and of equal amounts. By the 

 heat-dissociation the molecules of carbon are liberated along 

 the entire course of the discharge, and are, as the static 

 charges of the poles are equal, attracted simply in one half of 

 the field to the one pole and in the other half to the other 

 pole. 



The sulphur molecules liberated at the same time are, on 

 account of the great heat, not deposited on the poles. Indeed 

 in this decomposition, a yellow-brown mass is deposited on 

 the sides of the tube which is nothing else than the sulphur 

 condensed there. 



Silicon tetrachloride does not appear to be acted on at all 

 by the discharge. Attempts were made to electrolyse the 

 haloid compounds of mercury in form of vapour. The results 

 were all negative, which may, how r ever, be owing to the great 

 difficulties encountered in carrying out the experiments. 



It would seem, finally, that some of the phenomena described 

 are true electrolyses in part. Others seem to be " Thermo- 

 lyses," that is, the compounds are simply dissociated by the 

 heat of the discharge. The predilection of the atoms thus 

 liberated for electricity of different kinds would make them, 

 like pith-balls, fly to the pole having the charge opposite their 

 own, and thus give the entire phenomenon the appearance in 

 all respects of a true electrolysis, while in reality there is the 

 greatest possible difference. 



It is very difficult to separate the " Thermolysis " from 

 electrolysis in the experiments I have described, and the 

 phenomena indicate that in most cases described they go hand 

 in hand 



Washington University, 

 St. Louis, March 1892. 



