Page:Proceedings of the Royal Society of London Vol 60.djvu/229

Rh nate, took to diffuse to the same extent was 1719″, giving an average rate per millimetre of 21′49″.

(c) AcetyleneThe gas was prepared from pure calcium carbide by the action of water. It dissolved completely in alcohol. The time required for diffusion was 1550", giving a rate per millimetre of 19’37".

Assuming the times for the diffusion of these gases to be proportional to the square roots of their densities, we have—

For oxygen 5'37" * ^ 16 = 21-39". Found 21-49". a/1-0082 For acetylene 5*37" x / 1 3 g 08 _ 19.29». Found 19.37". v71-0082

This process may therefore be trusted to give fairly accurate results when applied to test the rates of diffusion of gases of known purity.

To ascertain whether a separation could be easily effected, experiments were made (a) on a mixture of oxygen and carbon dioxide, and ( h) on a mixture of hydrogen and helium.

(a) Oxygen and Carbon Dioxide.—The original mixture contained 36 per cent, by volume of carbon dioxide. It was split into two approximately equal portions ; each of these was again split into two. The most diffusible part contained 30-2 per cent, of carbon dioxide, and the least diffusible part 41-0 per cent.

( b) Hydrogen and Helium.—The original mixture contained 50 per cent, of each gas, and its volume was 38 c.c. 19 c.c. were diffused ; this was again halved, 9‘5 c.c. being passed through the pipe; and finally another diffusion of the 9‘5 c.c. yielded 4T2 c.c. of mixed gases. The hydrogen was removed by explosion with oxygen. This mixture now consisted of 67 per cent, of hydrogen and 33 per cent, of helium.

From these experiments it is seen that a partial separation of such gases is easily carried out.

Four hundred c.c. of argon, newly circulated ovur red-hot magnesium until spectroscopic traces of nitrogen were carefully removed, was diffused according to the subjoined scheme :—