318 J. Troiobridge — Spectra of Hydrogen, etc. 



of l~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 what- 

 ever 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 pres- 

 ent stage of this investigation with gases submitted to powerful 

 electric discharges? It seems to me 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 vapor present. 



3. The dissociation of this water vapor in the case of tubes 

 filled apparently with pure hydrogen, under the effect of a 

 strong steady current of electricity, shows an electrolytic action 

 closely analogous to that of the voltaic cell. In the case of 

 electrolytic copper- terminals in an atmosphere 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 oxygen 

 is set free from commercial aluminum and magnesium. 



5. Certain carbon bands are always present in glass tubes 

 filled with hydrogen, nitrogen, oxygen and ammonia gas not- 

 withstanding the greatest care which may be taken in submit- 

 ting them, during the process of exhausting, to a high tempera- 

 ture, when powerful discharges are employed. 



6. The brilliancy of the light of tubes filled with hydrogen 

 diminishes as the process of the dissociation of water vapor 

 goes on and the resistance of the tube increases. It is possible 

 to raise such a tube to the X-ray stage from a pressure of 

 l-2 mm merely by the application of a strong steady current. 



7. The X-rays excited by the application of a steady cur- 

 rent are due to the radiations set up by the dissociation of 

 highly rarified water vapor. 



Jefferson Physical Laboratory, 

 Harvard University. 



