Page:Proceedings of the Royal Society of London Vol 60.djvu/485

452 To facilitate the absorption of the gases during the experiment, the vacuum-tube was kept cool by a water-jacket, G, closed at the bottom by a cork fitting tightly round the tube. When it was necessary to heat the vacuum-tube, the jacket could be loosened from the cork, and slipped up the side-tube B, which was bent round, and extended vertically for about 10 inches in a straight line with the vacuum-tube.

The gas was made to circulate for about six hours, and at the end of that time the tap F was closed, the tap E was opened, and the apparatus thoroughly exhausted. The jacket G was then raised, and the gas expelled from the platinum by heat was pumped off. From mixtures containing very little helium, a small quantity of that gas was separated, mixed with a trace of argon.