﻿by Elements in the Electric Discharge- Tube, 225 



owing to the low pressure, but diffuse into the tube cooled by 

 liquid air, or become absorbed by the glass, and thus remain 

 in the atomic condition. They retain all the chemical activity 

 of the atoms. Langmuir also found that when the liquid air 

 was removed, some of the atoms would come off the glass 

 and recombine with other atoms to form molecules. These 

 molecules could not be recondensed by replacing the liquid 

 air. This gas which would not again disappear he termed a 

 " non-recondensible" gas. 



This hypothesis, which is applicable to very low pressures, 

 cannot hold at the pressures used in the present work. The 

 gas in the atomic condition can scarcely move from the 

 discharge-tube for a considerable distance and still retain 

 its atomic nature. The " non-recondensible " gas found by 

 Langmuir is probably hydrogen in its normal state. 



When nitrogen gas disappears in the discharge-tube, 

 practically none of it can be reliberated, even when the tube 

 is heated to the softening point. This fact indicates a 

 striking difference between the disappearance of hydrogen 

 and nitrogen. If chemical compounds are formed by the 

 absorption of the gases, this difference can be explained 

 in terms of the difference in the stability of the hydrides and 

 nitrides produced. 



The chemical action may take place between hydrogen and 

 the vapour of the element, and also it may occur at the 

 surface of the solid. The majority of the elements studied 

 have such small vapour-pressures that a very small propor- 

 tion of the action is due to the vapour. The active condition 

 of the gas must be caused by the ions, although results seem 

 to indicate that the number of active atoms or molecules in 

 the gas is of a much higher order than the number of ions 

 present in the gas at the instant of recombination. 



The absorption is not due entirely to chemical action, as the 

 law of constant proportions does not seem to be followed. 

 It is of significance, however, that the rate of disappear- 

 ance of the gas increases, and the final pressure attained 

 decreases, as the temperature of the discharge vessel is 

 lowered. This arises from the lowering of the vapour- 

 pressure of the compounds produced, with the result that 

 the final pressure reached is lowered. 



Although the formation of hydrogen sulphide in the 

 discharge-tube by the action of the activated hydrogen 

 on the sulphur will not explain the disappearance of the 

 gas, it does indicate the production of a modified form of 

 the gas which is able, possibly, to form other compounds 

 with sulphur in addition to hydrogen sulphide. 



Phil Mag. S. 6. Vol 44. No. 259. July 1922. Q 



