tf “~~ 
New York AGRICULTURAL EXPERIMENT STATION. 263 
. . . . e B 
with a fair degree of approximation by the equation, G3 
Ce 
8 and p being constants dependent in value upon the active sub- 
stances and the conditions. The formula has been found to hold by 
Freundlich, Walker and Appleyard, and Schmidt. (loc. cit.) In 
the experiments of Schmidt, p was found to vary from 2 to 10, while 
’ 
in those of Freundlich (loc. cit. p. 396) p did not vary greatly from 
2 in most cases. When p becomes unity, the formula applies to the 

; ae 19- Gy 
case in which — = constant. 
9 
“(5) The velocity with which the formation of an_adsorption 
compound occurs decreases continually as more substance is ad- 
sorbed and the adsorption approaches equilibrium.’ In another 
article van Bemmelen! says: ‘‘ The adsorption begins with great 
speed and decreases continually as more substance is adsorbed and 
equilibrium is approached. With constant shaking, the latter 1s 
usually reached in one to three hours.” 
To the above we may add the two points following: 
(6) The reaction approaches a true equilibrium, which can be 
approach from either side, as stated by Ostwald,? and as shown 
by the work of Freundlich,’ and laso by Walker and Appleyard. 
(7) Ostwald expresses graphically as follows the characteristic 
relation between the concentration of the solution and amount of 
solute adsorbed. Using rectangular coordinates, if one plots dilu- 
tions of the solution as ordinates and amounts of solute adsorbed 
as abscissae, the resulting curve will be nearly a hyperbola. 
Of the above, the first and most important point corresponds 
entirely with the facts observed in the reaction between casein and 
acids. There are no definite combining proportions. 
None of our data bears upon the second point, since the casein 
was all prepared and kept by one uniform method. 
The third statement is in harmony with our results. In the cases. 
tested, temperature was found to have a considerable influence upon 
the amount of acid fixed. 
*Ztsch. anorg. Chem., 23:345. 1900. 
> Lehrb. d. Allg. Chem. 2d Aufl. 1, 1903. 
Seam ects +p. 250, 
plocecit: 
