﻿224: Dr. F. H. Newman on Absorption of Hydrogen 



also lost its bright appearance. This was due to the action on 

 it o£ the sulphide of hydrogen. The mercury surface 

 remained quite clear when the sodium-potassium alloy was 

 tested. 



Sulphur and the alloy were selected for tests because the 

 chemical actions in these cases give rise to compounds whose 

 effects can be noted easily. It is extremely difficult to 

 examine phosphorus and iodine in this way owing to their 

 high vapour-pressures. A possible test would be the com- 

 parison of the vapour-pressures before and after absorption 

 of hydrogen had taken place. 



These two experiments indicate that the chemical action is 

 not due directly to the ions in the discharge-tube, as they 

 were all eliminated by the charged platinum strips before 

 reaching either the alloy or the sulphur. 



Wendt * showed that hydrogen can be activated by the 

 passage of a-rays through the gas, and it has been shown by 

 the author f that the active modification so produced is able 

 to react chemically with sulphur and the alloy of sodium and 

 potassium. 



4. Discussion of Results. 



The disappearance of gas in a vacuum-tube is due probably 

 to several principles, some of which may be fundamental. 

 It is certain, however, that any attempt to explain the 

 principles by the same theory would lead to conflicting- 

 results, but the processes occurring can be divided into 

 two classes, chemical and mechanical. There is much 

 evidence that the gas can be caused by the electric 

 discharge to adhere to the solid parts of the discharge-tube 

 in some manner which is at present unknown. In many 

 cases a portion of the gas can be reliberated by heating 

 the vessel, but no reason can be advanced for the non- 

 reliberation of the whole of the gas which has disappeared. 



Langmuir assumes in the paper previously quoted that the 

 hydrogen in the presence of an incandescent filament under- 

 goes dissociation. The gas shows abnormal thermal 

 conductivity at high temperatures, due to its atomic nature. 

 The dissociation does not occur apparently in the space round 

 the wire, and is not due to the impacts of the gas molecules 

 against its surface, but takes place only among the hydrogen 

 molecules which have been absorbed by the metal of the wire. 

 Some of the atoms leaving the wire do not meet other atoms, 



* Nat. Acad. Sci. Proc. vol. v. (1919). 

 t Phil. Mag. vol. xliii. (1922). 



