1918-19.] The Adsorption Isotherm at Low Concentrations. 55 
charcoal, obtained positive adsorption followed by negative adsorption with 
potassium chloride, and negative adsorption with sodium chloride, potassium 
sulphate, and sodium sulphate. He corrects for the water adsorbed (w), but 
as the correction is often much greater than the amount corrected, it is 
not surprising from its nature that he finds the sequence of adsorption the 
same as the general sequence of properties of the solutions involved. 
Summary. 
1. It is pointed out that for very small adsorptions the adsorption law 
appears to be 
a = a 0 C 
for both gases and solutions. 
2. The general form of the adsorption curve for solutions is deduced 
from the above conclusion and found to agree with the results of different 
observers. 
The author wishes to thank Professor James Walker, F.R.S., for his 
assistance in the presentation of this paper. 
{Issued separately May 26, 1919.) 
