ARTICLE XII. 
On the Employment of Polarized Light in studying various ques- 
tions of Chemical Mechanics. By M. Bior*, 
[From the Annales de Chimie, t. x., 1844.] 
Section I.—General considerations which serve as bases for 
the theoretical formule applicable to this class of experiments. 
1. HAVING seen, in the Proceedings of the Academy of 
Berlin, that Professor Mitscherlich has entered upon the inves- 
tigation of the molecular actions exercised upon polarized light 
by saccharine substances, as well as by tartaric acid in its various 
states of combination, and being persuaded that so inventive a 
philosopher having once entered upon this path of investigation 
cannot fail to reap a rich harvest of discoveries, it has occurred 
to me that I might still, with advantage, remove some of the 
difficulties of detail which are here met with, and show the ex- 
tent of the theoretic deductions which may be derived from it, 
by stating the unexpected results to which it has led me respect- 
ing the internal state of liquid systems, in which several bodies, 
placed in contact, react invisibly upon each other, by their re- 
ciprocal affinities, without being mutually decomposed. These 
results, in the most simple cases, follow from the experiments 
already recorded in the Mémoires de l’ Académie des Sciences, 
particularly in vols. ii. xiii. xv. xvi., as well as in the Comptes 
Rendus of the Academy, which have been published subsequently. 
I shall complete them here by several series of observations made 
during the summers of 1835, 1836 and 1837, on liquid systems 
formed by tartaric acid, boracic acid, and water, at constant tem- 
peratures, varying in each series the relative proportions of the 
three bodies, in every degree compatible with the state of li- 
quidity. The effects produced on polarized light by these 
systems have been observed, in each case, with every propor- 
tion of boracic acid which could be successively introduced ; 
and they have been found capable of being connected by the 
same form of numerical law which systems less complex, or 
* [The editor is indebted to the Rev. Prof. Lloyd, F.R.S., &c. of Trinity Col- 
lege, Dublin, for his kind assistance in revising the translation of this memoir. ] 
