202 REPORT OF THE CHEMIST OF THE 
IS THE REACTION ONE OF ADSORPTION ? 
By adsorption is meant the process whereby a solid substance 
A in contact with a solution of a dissolved substance B concentrates 
B upon its surface, withdrawing a portion of B from solution with- 
out forming with it a definite chemical compound. 
In regard to the characteristics of adsorption reactions, we quote 
the five characteristic points given by van Bemmelen for reactions 
of this class: 
“(1) The adsorbed amounts stand in no equivalent proportions 
to the adsorbing mass. 
(2) The composition varies with the structure of the adsorbing 
substance and with all modifications which the latter undergoes by 
reason of its method of preparation, age, heat or action of other 
substances. 
(3) The composition varies with the temperature, 
“(4) Likewise with the concentration of the solution, in case sub- 
stances are adsorbed from their solutions; and the composition 
varies in such manner that the adsorption factor k in the formula 
Cy 
Par F(k) is not constant, but is dependent upon the concentration 
2 
of the solution according to a function that we do not understand. 
. ” C, 
In general, however, c, increases more slowly than c,”’ ( — decreases 
9 
- 
as concentration increases). 
c, = amount of solute adsorbed per unit mass of adsorbent. 
c, == concentration of solute in solution. 
F == unknown function. 
In another article? however, van Bemmelen says: ‘‘ When the 
adsorptive power is small and the solution not concentrated, then, 
St Cea Cte 
between certain limits of concentration, —' is nearly constant.” 
» 
Lass Cy : 
In regard to the variation of —, while, as van Bemmelen 
Cy 
states, an entirely general and accurate formula is unknown, 
the relation in a large proportion of adsorptions, can be expressed 
*Ztschr. Anorgan. Cheim., 36:381. 1903. 
*Ztschr. Phys. Chem., 18:33. 1895. 
