of tie gas was confined over a large quantity of boiled water, and the residue taken for examination.
R aillere....................... 3‘7 c.c. taken, DO 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 (Eufs 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, D3, 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 process, 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 vacuumtube 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 o|her gas, other than argon and helium, be present in the residue front 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.
