128 Sir James Devvar. The Separation of the most [June 15, 



Some 2 years later I improved the method of separation of the vola- 

 tile air gases. The process is fully described and illustrated in my 

 paper on "Problems of the Atmosphere."* Its success depends upon the 

 continuous direct liquefaction of air at atmospheric pressure combined 

 with a device which enables the more volatile gases to be trapped and 

 separated. In this way some l/35,000th of the volume of the air 

 liquefied is collected as a gaseous mixture, having the composition 

 38 per cent, of nitrogen, 4 per cent, of hydrogen, and 58 per cent, of 

 mixed helium and neon. After sparking to remove the nitrogen and 

 hydrogen, a gaseous mixture of helium and neon containing a little 

 argon was obtained. This mixture had the composition of 16 percent, 

 helium and 84 per cent. neon. In both methods of treatment it will 

 IKJ noted the liquefaction of the air was the essential preliminary opera- 

 tion, to be supplemented in the one case by the use of liquid hydrogen, 

 in the other by sparking to remove the nitrogen. The paper already 

 communicated to the Royal Society, entitled " The Absorption and 

 Fi 1 Thermal Evolution of Gases Occluded in Charcoal at Low 

 Temperatures," in which the greatly increased power of occlu- 

 sion possessed by charcoal at low temperatures is proved, 

 suggested an inquiry into the limits of gaseous pressure 

 reached by such means of condensation. 



With this object a narrow tube CE, fig. 1, was sealed to an 

 ordinary spectroscopic sparking tube AB, and at the end E 

 an enlarged space was blown out capable of holding a few 

 grammes of cocoanut charcoal. After the charcoal had been 

 freed from gases by heating and exhaustion and the poles 

 cleared by sparking during this operation, pure and dry gases 

 like oxygen, nitrogen, air, carbonic oxide, hydrogen, neon 

 and helium could be admitted at different pressures and the 

 tube with its charcoal chamber attached sealed off. 

 On placing the charcoal end of the apparatus in liquid air 

 e gas in each case was rapidly absorbed and the vacuum 

 duced reached the phosphorescent stage in all cases with 

 3 exception of hydrogen, neon, and helium. A small 

 Orookess radiometer, full of air at atmospheric pressure, with 

 iircoal I tube attached, became quite active to heat radiation 

 en the charcoal was cooled for half a minute in liquid 

 ) test the amount of exhaustion reached by the use of a 

 given weight of cocoanut charcoal I sealed on a tube contain- 

 grammes to a large electric discharge tube of 1300 c c 

 'ty filled with air at atmospheric pressure. On cooling 

 30 luin of merlT ^^ Hquid air the P ress ^e diminished to 

 the tube ii i-ill ' "^ Same ex P er i ment but starting with 



n atmosphere, the exhaustion reached was 

 ' Roy. Inst. Proc.,' 1902. 



