706 Disappearance of Gas in the Electric Discharge. 



is thought that part o£ the gas is held to the walls in its 

 original form by a covering layer of tungsten. 



§ 16. Argon disappears like nitrogen with much blacken- 

 ing of the bulb ; but the gas can be restored by baking- 

 together with hydrogen produced by the bombardment of 

 the glass. 



§ 17. Mercury has not been proved to disappear. The 

 discharge through the vapour liberates large quantities of gas 

 from the glass, even if they have been previously baked in a 

 high vacuum. 



5 18. The conclusions based on this part of the work are 

 given on p. 691. 



§ 19. Some of the relevant properties of phosphorus vapour 

 are stated. 



§ 20. Phosphorus vapour disappears rapidly in the dis- 

 charge, being converted into red phosphorus which is de- 

 posited on the walls. The glow potential of phosphorus 

 vapour is anomalous. 



§ 21. Hydrogen, carbon monoxide, and nitrogen when 

 mixed with phosphorus vapour disappear in the discharge 

 together with the phosphorus. A lower final pressure of gas 

 can be reached with a given applied potential in the presence 

 of phosphorus than in its absence. This fact is correlated with 

 the abnormal glow potential of phosphorus vapour. 



§ 22. It is asked whether there is any evidence for the 

 prevalent view that the action of phosphorus in removing 

 gases in the discharge is chemical. Evidence against this 

 view is adduced thus : — 



§ 23. The state of these gases when they have disappeared 

 in the presence of phosphorus seems not to differ from the 

 corresponding state in the absence of phosphorus. 



§ 24. There is no indication of a " law of constant 

 proportions." 



§ 25. The state of the glass walls modifies profoundly the 

 absorption of gas. 



§ 27. An alternative theory of the effect of phosphorus is 

 proposed. It is suggested that the deposited red phosphorus 

 covers the deposited gas and prevents it from being liberated 

 again by bombardment. At the same time it provides a new 

 surface on which gas can be absorbed. 



