Kohlenberg—Osmosis and Osmotic Pressure. 215 
hausted. It is to be noted, however, that since chloroform is 
more soluble in water containing ether than in pure water, the 
aqueous layer B will take up more chloroform after becoming 
charged with ether. Thus some of the chloroform is making 
its way upward into the aqueous layer B, from which it also 
passes in part into the ethereal layer C. 
It is clear then that the ether of layer C is making its way 
through the aqueous layer B into the chloroform layer A, and 
that on the other hand the chloroform is passing into the 
aqueous layer B charged with ether and further into C. Thus 
we have currents of ether and chloroform going in opposite di¬ 
rections. The movement of the chloroform as to quantity is, 
however, extremely slight as compared with that of the ether; 
and so the movement of the latter practically predominates and 
the ethereal layer is finally absorbed. It must be borne in 
mind, however, that water, being somewhat more soluble in 
chloroform charged with ether than in pure chloroform, will to 
a slight extent go into the layer A as it becomes enriched with 
ether; and, as has already been remarked, some water also 
passes into the layer C, for water is somewhat soluble in ether. 
When the change is complete, we have, as stated above, a lower 
layer consisting of chloroform and ether saturated with water, 
and an upper layer of water saturated with ether and chloro¬ 
form. 
The rate at which this process goes on depends on the tem¬ 
perature and upon the pressure, but also upon the thickness of 
the aqueous layer B and the area of the surface of contact with 
the ethereal layer C and the chloroform layer A.i It is further 
clear that the process would be hastened if each of the layers 
A, B, and C were continually stirred, for by so doing the slow 
processes of diffusion would be aided and the changes in con¬ 
centration which take place in the layers where they are in con¬ 
tact with one another would be lessened. 
Summed up then, the observed change goes on because ether 
is soluble in water, but much more readily soluble in chloro¬ 
form, so that latter is able to extract ether from the aqueous 
solution of ether, B. The chloroform—ether solution in A 
may be regarded as a solution of chloroform in ether, especially 
