448 Gaseous Constituents of certain Mineral Substances, fyc. 



of the gas was confined over a large quantity of boiled water, and 

 the residue taken for examination. 



Raillere 3'7 c.c. taken, 1*0 c.c. residue. 



Des CEufs 8-5 4'0 



Csesar 2'2 0'5 



Espagnol 8*0 ,, (not measured). 



The residue showed the helium lines rather more strongly. 



The Des CEufs gas was submitted to fractional diffusion by the 

 method described in the following paper. 



The gas was divided into two portions by diffusion through a. 

 porous plug. These two fractions were then diffused separately, the 

 light fraction of the heavy gas, and the heavy fraction of the light 

 gas forming an intermediate fraction, This was again separated by 

 diffusion into a heavy and a light portion, which were mixed with the 

 heavy and light fraction obtained in the second stage. The process 

 was repeated four times, and the resulting fractions, after sparking 

 with a little oxygen, were rediffused so as to obtain the lightest sixth 

 of the light fraction, and the heaviest sixth of the heavy fraction. 



In a Pliicker tube, the helium line, D 3 , appeared somewhat stronger 

 in the light gas, but the difference was not so marked as might have 

 been expected. Neither of the tubes showed any lines other than 

 those of the argon or helium spectrum. 



The other samples of gas were not submitted to the diffusion pro- 

 cess, as it did not seem probable that any results of value would be 

 obtained. 



In another paper it is shown that separation of helium from argon 

 can be effected by taking advantage of the absorption of that gas by 

 the platinum splashed on to the walls of the tube during the passage 

 of the discharge. The gas is made to circulate at about 3 mm. 

 pressure through a vacuum -tube with platinum electrodes, and kept 

 cool by a water-jacket. The helium, together with any nitrogen or 

 carbon compounds that may be present, is absorbed by the platinum, 

 and may be liberated by heating the tube with a Bunsen's burner. 

 The heavier fraction of the Des CEufs gas, and some of the gas from 

 the Raillere were treated by this process, and the gas liberated from 

 the platinum on heating was in each case introduced into a vacuum- 

 tube with aluminium electrodes. The tube showed a banded spectrum 

 which disappeared as the nitrogen was absorbed by the heated 

 aluminium, leaving only normal helium at low pressure and a trace 

 of argon. If any other gas, other than argon and helium, be present 

 in the residue from the gas evolved from these various springs, after 

 removal of the nitrogen, the methods employed have totally failed to 

 bring it to light so far. It certainly cannot be present in any 

 measurable quantity. 



