122 
Proceedings of the Royal Society of Edinburgh. [Sess. 
It is clear from fig. 1 that the gas-capacity of a cylinder intended to 
hold nitrogen under compression may be increased by filling the cylinder 
with dry cocoanut charcoal. The advantage gained from the charcoal is 
especially marked for pressures below 50 atmospheres. When blown off 
from 35 atmos. abs. to 1 atmos. abs., for example, a cylinder containing 
cocoanut charcoal would discharge 66 per cent, more nitrogen than the 
same cylinder containing no adsorbent. Put in another way, the results 
indicate that a cylinder of 1 cubic foot water-capacity filled with dry 
cocoanut charcoal and charged with nitrogen at 21 atmospheres would hold 
Fig. 2. 
A , Oxygen in colloidal silica. 
B, Nitrogen in common wood charcoal. 
C , Nitrogen in birch charcoal. 
D, Hydrogen in colloidal silica. 
F, Hydrogen in German impregnated charcoal. 
F, Nitrogen in German impregnated charcoal. 
a total volume of 50 cubic feet of gas, of which 43'5 cubic feet would be 
discharged on the pressure being released to atmospheric. Had the cylinder 
not held charcoal it would require to have been charged to 44*5 atmos. abs. 
to yield the same volume. The increase of available volume could probably 
be raised from 66 to about 80 per cent, at 35 atmospheres by ramming the 
charcoal forcibly into the cylinder. A similar but smaller difference is 
observable for hydrogen (compare curves B and E , fig. 1). 
As gaseous adsorption is much improved by cold, it follows that a 
cylinder containing charcoal could be charged with a given mass of gas at 
low temperature (obtained, say, from a Claude or Linde plant) with a less 
expenditure of energy than if charged at ordinary temperature. 
The influence of moisture (compare curves A and G, fig. 1) points to the 
need for dryness in both adsorbent and gas if this method of gas storage 
be adopted. 
