382 BlOT ON THE EMPLOYMENT OF POLARIZED LIGHT ~ 
According to this, having proved by experiment that, in each’ 
series in which m is constant, the [«] follow a hyperbolic 
law whose coefficients we determine, it is clear that the [a]' 
will also follow a similar law whose coefficients A and B will 
to 1; so that 
merely have a less value in the relation of ee 
the chemical group composed of tartaric acid and water having: 
the molecular power [«]', offers, relatively to the ponderable 
proportion 8 of boracic acid present, a Jaw of progressive con- 
nexion, analytically similar to that which the simple group of 
tartaric acid presents in the purely aqueous solutions of this 
acid, relatively to the ponderable proportion e of water with 
which it was then associated, as we have established in § 55 of 
the preceding section. For the hyperbola of fig. 5, Plate V., 
1 
n+1 
of the same nature, as well as both similarly placed and applied 
to the analogous elements of the two systems, whence it clearly 
results that their similar course represents similar phenomena _ 
of molecular reaction amongst different chemical groups. There 
is no dissimilarity except in the absolute values of the numerical 
elements. 
67. Lastly, if we consider the mean group composed of tar- 
taric acid and water, whose power is [a], as forming with bo- 
racic acid a uniform combination indefinitely variable in propor- 
tion as the amount 6 of this latter acid increases, each mixed 
system thus constituted would realize the case of liquids chemi- 
cally homogeneous which we have treated of in §§ 8 and 27 of 
the first section. Calling then [«]" the molecular rotatory power 
of the complex groups thus composed, we should have, as in the 
paragraphs cited, 
modified by the factor and the hyperbola of fig. 2, are both 
Ri aes 
lal sary 
Now, for each series of such systems, where the relation of the 
weight of water to that of the tartaric acid is m, experiment gives 
us the hyperbolic relation 
a BB 
—= on | oo, 
FP Seki eR PTC GF (Ht) 
A, B, C being three numerical coefficients, functions of n alone, 
and constants in one and the same series. There will therefore 
result 
