616 Stiles and Jargensen.—Stndies in Permeability. II. 
curves in shape, and this is confirmed by plotting curves between the time 
and the logarithm of the concentration (see last column of tables and 
Fig. 4). 
The relation between time and concentration is then given by the 
equation 
— log C = kt +k' .(i) 
and if x represents the amount of acid absorbed at any time we have 
— log (A — x) = kt + k r 
where A is the original quantity of acid present. 
If this is taken as unity we have k' — o, and 
k = ~ lQ g 
dx 
The rate of absorption is then given by the equation 
dx 
~dt 
=k(A-x) .(2), 
i. e. the rate of absorption is proportional to the concentration at any 
time and to the constant k, and k has the same value in equation (2) 
as in equation (1). 
From measurements of the curves obtained from experiments and 
shown in Fig. 4 we have the following values for k at different temperatures : 
Temperature . k 
o° o-o 36 
io° 0-081 
20° 0-174 
3O 0 0-380 
i. e. the rate of absorption is increased by a rise of io°C. as follows : 
from o° to io° 2*22 times 
„ io° „ 20° 2-17 „ 
» 20° „ 3°° S' 18 >» 
The rate of absorption is therefore increased by about 2-2 times 
for a rise of io°C. 
Now if the absorption of the hydrogen ion were controlled by simple 
diffusion into the cell-tissue, one would not expect the increase in its 
rate of entrance to be of this order. Rather an increase in much lower 
proportion would be expected, of about the order of 1 : 3. 
As regards the effect of temperature on the rate of adsorption, the 
coefficient seems to be of the same order as that of diffusion; certainly the 
van’t Hoff rule is not followed, 
