16 THE ROYAL SOCIETY OF CANADA 

and since dP 
q 
Qh =a IRAN Rotor oe NOK X 
- | ae 
P a Ege f \ 11€ 
If now we assume that the same law governs the diffusion of the 
emanation which holds for a small quantity of one gas diffusing into 
a second we may take 

K, — — where p is the pressure of the gas in which the diffusion 
P 
takes place and A, is a constant. 
We have then 

os \ ca 
P = \ p p 
RES (e 
VAUX, 
In order to find the pressure corresponding to a maximum deposit for 
a selected value of x it suffices to apply the condition 
dP 
== =i 
dp 
ae 1 ray 
This gives — — | Ly eel 
Vp N A, 
A ae 
Tay a mea EAS LE WP OR A (1) 
wer À 
i.e., the pressure corresponding to the maximum deposit at a point 
at a distance x from the salt, should, with the assumptions made above, 
be inversely proportional to the square of the distance of the point 
under observation from the surface of the salt. This result it will 
be seen is distinctly at variance with the law of distribution discovered 
by Kennedy. 
