Absorptio7i of Gases in Vacuum-Tuhes. 



487 



then diminished to zero. At first sight, this would seem to 

 be in direct opposition to the disintegration theory, but an 

 examination of Tyndall and Hughes' curves shows that the 

 case of hydrogen lends additional support to this theory. 

 Fig. 6 is reproduced from their paper. In air, the gradient 



Fis-. 6. 



200 400 600 800 1000 1200 !400 1600 volts 

 Cathode fall of potential 



in the rate of disintegration increases as the cathode-fall 

 increases ; the rate of absorption also increases under the 

 same conditions. In hydrogen, the gradient in the rate of 

 disintegration soon decreases with increase of cathode-falL 

 tending towards zero ; the rate of absorption also decreases 

 with increasing cathode-fall, tending towards zero. The 

 exact parallelism between the rates of absorption and the 

 gradients in the rate of disintegration in these widely 

 divergent results is an excellent verification of the theory 

 advocated in this paper. 



8. General Discussion. — The absorption is probably a 

 phenomenon of some complexity. With metallic electrodes,, 

 the major portion is due to absorption of gas by the dis- 

 integrated metal. Some may be due to the liberation of the 

 alkali metals by electrolysis of the glass, and chemical 

 combination of these metals with the gas. Experiments in 

 tubes made of other materials than glass would be of great 



