Absorption of Gases in Vacuum- Tubes. 



481 



means o£ a current. This electrode was kept at white heat 

 during some hours before an absorption experiment was 

 commenced. During this time, gas was evolved in gradually 

 diminishing quantity : the heating was continued till gas 

 ceased to be evolved. 



Fisr. 2. 



■20 mm 



\- 



\ 



\ 



\ 



\ 



"\ 



\ 



*\* 



\ 



4 cm. 



.MiNUTES. 



\ 



K- 



.3 5 cm. 



10 2 30 40 50 60 \70 60 90 100 110 N 



*\> 



!\ 



With the platinum loop as cathode an absorption of gas 

 was obtained, the pressure falling from 0*495 to 0*340 mm. 

 On heating the cathode to a white heat, none of the absorbed 

 gas was recovered. 



The same was the case with the loop as anode — no absorbed 

 gas was recovered. It is therefore unlikely that the cathode 

 or the anode absorbs gas mechanically. 



6. Experiments with Normal Cathode-FalL — Experiments 

 were now performed to see what relation could be found to 

 exist between the rate of absorption and the cathode-fall. 

 With the normal cathode glow — i. e. when the cathode glow 

 did not cover the whole of the cathode — practically no 

 absorption was obtained with copper electrodes in air, 

 oxygen, hydrogen, and carbon dioxide. The gas-pressure 

 remained sensibly constant, although currents were passed 

 continuously for long periods. The following table shows the 

 maximum variation of pressure in nineteen experiments. 



Now, it was shown by Tyndall and Hughes in the paper 

 already referred to, that there is practically no disintegration 



Phil. Mag. S. 6. Vol. 31. No. 185. May 1916. 2 K 



