Disappearance of Gas in the Electric Discharge. 689 



absorption has not been found, although a quantity has been 

 -absorbed equal to at least five times that representing a 

 monocular layer on the walls. 



If the vessel is now baked (the temperature of baking, so 

 long as it is over 600° K. is apparently immaterial), the 

 greater part of the gas is restored. Most of it is restored as 

 C0 2 , and not as CO. The amount of CO liberated from the 

 walls was never found to be greater than ]. a monomolecular 

 layer. But if it is supposed, as indicated in § 10, that the 

 C0 2 is formed from the CO by abstraction of carbon, so that 

 a given volume of C0 2 represents double that volume of CO, 

 then at least 90 per cent, of the gas can be restored by 

 baking. It was not investigated whether there was also 

 water vapour in the restored gas, but it now appears probable 

 there was. Water vapour seems always to be produced when 

 a discharge is passed in a vessel made of glass (lead-soda) 

 used in these experiments. 



15. The disappearance of nitrogen. — Nitrogen disappears 

 from the vessel under the action of the discharge, exactly as 

 does carbon monoxide, in apparently unlimited quantities. 

 But at the same time the filament wastes rapidly and the 

 walls become covered with a black deposit. Some blackening 

 always occured after prolonged operations in hydrogen and 

 CO, but it was altogether of a lesser order. In nitrogen, 

 absorption of gas and blackening of the glass (measured by 

 the wastage of the filament) are roughly proportional. 



When the walls are heated up to the softening point of 

 the glass, only a very small proportion of the gas absorbed 

 is evolved ; and much of this gas is not nitrogen. The 

 nitrogen cannot be liberated in any quantity by such baking. 

 (Again no inquiries for water vapour were made.) This 

 fact was taken at first to indicate the formation of Lang- 

 muir's nitride WN 3 by reaction between the tungsten and 

 the gas ; indeed, Langmuir asserts that the compound is 

 formed in the discharge. On the other hand, he insists that 

 the compound is brown ; while the deposit on the walls was 

 grey or black, and indistinguishable in colour from that 

 formed in other gases. An alternative (or, perhaps, addi- 

 tional) explanation of the disappearance of nitrogen will be 

 indicated later ; it is that the liberation of the nitrogen from 

 the walls is prevented by the deposition over it of tungsten 

 spluttered from the cathode. 



16. The disappearance of argon. — The gas employed always 

 contained about 5 per cent, of nitrogen, but was free from 

 oxygen . 



