110 ROYAL SOCIETY OF CANADA 
mass. These experiments will indicate if the absorption depends upon 
the total mass of charcoal, or upon the total surface of the grains of the 
charcoal which is exposed to the emanation. The general theory 
advanced in this paper will hold good in any case. Until this point 
is settled no absolute value for s can be given, although, as shown above, 
its relative values for different temperatures of the same material, and 
for different materials, can be found. 
199 echo. | 
> Eu UK 
os SUN 




À nssoxerion OF ENANATION, 

+60 140 
TEMPERATURE, DEGREES CENTIGRADE. 
16. IF 
An idea of the magnitude of sV,, is given by the following approxi- 
mate figures, which refer to 2:9 gms. of charcoal. 
Temperature of Charcoal. SAVE 
210° C. 0.23 
100 0.70 
21 1.3 
—80 2.0 
For other quantities of charcoal these figures should be proportional 
to the quantity. 
Mention has already been made of some discrepancies from the 
mathematical theory in the experimental curves at low speeds of the 
air current. <A possible reason for this is that all the emanation atoms 
produced in the thorium tube may not, on account of some such action 
as absorption or diffusion, to reach the testing vessel at low speeds be 
