; 
326 BIOT ON THE EMPLOYMENT OF POLARIZED LIGHT j 
Srconp Puase.—The weight EK of the inactive liquid is insuffi- 
cient, or but just sufficient, to saturate P. | 
The general character of this second phase consists in the 
. a(P+E) : eee 
function —pry never being constant when the relation Pp 
varies. 
First Case.—The weight E of the inactive liquid is divided 
equally among all the constituent molecules of the active sub- 
stance, so as to form so many chemical groups identical among 
themselves and imperfectly saturated. For each given value of 
the relation = the mixed system is chemically homogeneous, 
but the constitution of the groups which compose it changes 
continually with this relation. 
Then, by virtue of § 23, the function 
a 
18 
varies continually for a same inactive liquid, in proportion as 
the relation = changes, and it ought likewise to vary for the 
same value of this relation when the inactive liquid is dif- 
ferent. At least it could only preserve the same value in such 
circumstances, by a particular exception, as it expresses the ro- 
tatory power of the new chemical groups occasionally formed. 
For that reason the law of its variability cannot be foreseen. If 
this mode of variation subsists for all the values of the relation 
E : er ee wees . a(P+E) 
— relative to a same inactive liquid, without the function Spig7 
- 
ever becoming constant, this would prove that the active sub- 
stance cannot be completely saturated by the inactive liquid, 
whatever amount of it be employed. 
Second Case.—The total weight P of the active substance 
separates spontaneously into two portions, one of which com- 
bines with E to saturation, and the other remains free. 
Then, in virtue of § 24, the characteristic function 
a(P + EB) 
P83 
being calculated successively for different values of the relation 
= relative to one and the same inactive liquid, will be variable 
as the ordinate of a right line, of which 2 would be the 
