Disappearance of Gas in the Electric Discharge. 917 



apparently unconnected effects produced by the deposition of 

 salts by the method of (6]. In all that concerns the forma- 

 tion of the absorbing layer, phosphorus and the substitutes of 

 (6) behave similarly. (Pars. 17-19.) 



In other respects phosphorus (together with As, and 

 probably S and I) has a specific action. The explanation of 

 this action propounded in the previous papers is maintained. 

 (Par. 20.) 



The Quantity of Gas Absorbed. 



1. The previous experiments had shown that if a given 

 vessel is filled with gas mixed with phosphorus vapour and 

 a discharge passed through it, the quantity of gas that can be 

 absorbed depends on (1) the nature of the gas, (2) the 

 quantity of phosphorus present, (3) the state of the walls of 

 the vessel. It might also conceivably depend upon (4) the 

 amount of gas originally present, (5) the nature of the 

 discharge. If the form of the vessel is altered, it may also 

 depend (6) on this form, even if its volume is constant. 

 The possible effect (7) of the temperature has to be taken 

 into consideration. 



2. As to (1), the nature of the gas, the range open to 

 investigation is very limited. Chemical compounds are 

 excluded because they invariably undergo chemical change 

 when the discharge passes, so that the great complications 

 enter which have been fully discussed in the case of carbon 

 monoxide. Of the elements, the inactive gases are known 

 to be very little absorbed. Oxygen and the halogens attack 

 metals, and especially the incandescent filament. The only 

 remaining elements which have sufficiently high vapour- 

 pressures at room temperatures are hydrogen and nitrogen. 

 Hydrogen has been used throughout the greater part of these 

 experiments, and " gas" will always mean hydrogen unless 

 the contrary is st sted. Observations on nitrogen have been 

 made sufficient to show that in the absorption by means 

 of phosphorus its behaviour is almost identical with that 

 of hydrogen. In all cases a slightly greater volume of nitro- 

 gen than hydrogen can be absorbed ; the difference amounts 

 to about 10 per cent. ; the variations in the amounts of the 

 two gases absorbed as the conditions change are closely 

 parallel, and no distinction between them need be made in 

 respect of any of the conclusions which will be put forward. 



3. In order to examine factor (2), the quantity of 

 phosphorus present, it is practically necessary to use a new 

 vessel for each experiment on absorption. In the first place, 



