SECTION III., 1907. [85] TRANS. RS. oC, 
X\.—The Effect of Temperature and of Velocity of Gas Current on the 
Absorption of Radio-active Emanations by Charcoal. 
By R. W. Boyz, M.Se. 
(Communicated by Prof. E. Rutherford, F.R.S.) 
The experiments of Sir James Dewar in 1903 drew attention to 
the property possessed by the charcoal of cocoanut of absorbing gases 
in a remarkable degree. Since then this property has been investigated 
by several experimenters,’ and has been applied by Sir William Ramsay 
in separating the inert gases helium and neon from the air, and measur- 
ing the quantities in which they exist in the atmosphere. The results 
in the papers mentioned below may be summarized as follows :— 
1. The absorption of gases by cocoanut charcoal is greatly increased 
by lowering the temperature of the charcoal. 
2. The charcoal has a greater “ affinity ” for some gases than for 
others, there being something of the nature of a selective absorption. 
In consequence of this property it is possible to separate from one 
another, in some degree, the constituents of a mixed gas. The best 
example of such separation is found in the work of Ramsay referred to 
above. 
3. Of the inert gases of the argon family, argon is absorbed about 
the same as ordinary gases, but helium and neon in a much less degree 
and helium less than neon. 
4. The absorption is also influenced by the pressure of the gas in 
contact with the charcoal, the pressure concentration curves varying in 
a regular manner with the temperature. 
It was pointed out by Professor Rutherford, in a letter to Nature, 
October 6th, 1906, that this property of cocoanut charcoal also holds 
for the radio-active emanations, and in his letter are accounts of experi- 
ments demonstrating the fact. Professor Rutherford found that a slow 

*The Absorption and Thermal Evolution of Gases occluded in Charcoal 
of low Temperature.—Dewar, Proc. Roy. Soc., Vol. LX XIV, p. 122. 
The Separation of the most volatile Gases from Air without Liquefac- 
tion.—Dewar, Proc. Roy. Soc., Vol. LXXIV, p. 122. 
The Determination of the Amount of Neon and Helium in Atmospheric 
Air—Ramsay, Proc. Roy. Soc., May 24, 1905. 
The Law of Distribution in the Case in which one of the Phases pos- 
sesses Mechanical Rigidity. 
Absorption and Occlusion.—Travers, Proc. Roy. Soc., July 21, 1905. 
