378 The Spectra of Hydrogen. 



bands which Kayser & Runge* designate respectively as the 

 second and third cyanogen bands in the arc-spectrum of 

 carbon in air. 



Besides these bands, a number of single lines appear which 

 are common to all the gases. Among these, the most promi- 

 nent are : — 



3652 



4048 



4080 



4360 



In the tube filled with cyanogen many of the same lines that 

 appear in tubes with metallic terminals, filled with nitrogen, 

 are present besides the above. This is true to a certain 

 extent of the other gases ; and it is not surprising, since it 

 is to be expected that some atmospheric air is always present 

 as an impurity, 



The conclusions to be drawn from these experiments with 

 steady currents are similar to those we have deduced from 

 condenser-discharges. When elementary gases are introduced 

 into tubes with carbon terminals, and exhausted to a pressure 

 of 1-2 mm., and are submitted to continuous currents, we 

 obtain the spectrum of carbon, or some compound of carbon. 

 From the above results very little information can be obtained 

 as to what this compound is. The same spectrum is obtained 

 whatever gas is introduced into the tube ; and, moreover, 

 this is the same spectrum which is given by gaseous carbon 

 compounds in tubes with metallic terminals. What, then, are 

 the conclusions to be drawn from the present stage of my 

 investigation with gases submitted to powerful electric dis- 

 charges ? It seems to me that they are as follows : — 



1. Hydrogen is an insulator. 



2. The passage of electricity through hydrogen, nitrogen, 

 oxygen, and their gaseous compounds is conditioned by 

 the water-vapour present. 



3. The dissociation of this water-vapour in the case of tubes 

 filled apparently with pure hydrogen, under the effect of 

 a strong steady current of electricity, shows an electro- 

 lytic action closely analogous to that of the voltaic cell. 

 In the case of electrolytic copper terminals in an atmo- 

 sphere of hydrogen, pure copper is deposited from the 

 negative terminal, and a suboxide of copper at the 

 positive terminal. 



4. Under the effect of powerful condenser-discharges, 



* Abhandlungen der Akademie der Wissen. zu Berlin, 1889. 



