7. Recent Advances in Stereochemistry. 
By Pror. B. K. S1neu, M.A. 
[Read at the Nagpur Indian Science Congress. | 
The subject of my address to-day is stereochemistry in 
some of its modern developments. There are several reasons 
which have induced me to make this selection. One is that I 
have been especially interested in this branch of chemistry 
during the past few years; another which is even more impor- 
tant, is that the subject is receiving increasing amount of atten- 
tion from chemists at the present time. The subject of optical 
activity has furnished several important discoveries which have 
materially contributed towards the development of modern 
chemistry. The progress of chemistry has been mainly achieved 
as a result of the co-ordination of observed facts with a 
series of hypotheses, each closely related in point of time to 
the one preceding it. The atomic theory of Dalton, enunciated 
in 1803, and the hypothesis of Avogadro formulated in 1813, 
were two great theoretical developments which gave great 
impetus to chemical investigation, and led to the association 
of a definite physical meaning with the idea of molecular com- 
position. These however, ultimately proved insufficient for 
the interpretation of a large number of facts collected under 
their impetus. A further great advance was only made pos- 
sible when Kekule in 1858, introduced into chemistry his doctrine 
of valency and the law of the linking of atoms. ‘The concep- 
tion of molecular constitution followed as a necessary corollary 
LeBel independently demonstrated the all-important part 
which molecular configuration plays in the interpretation of 
certain cases of isomerism in organic chemistry. In 1815, Biot 
observed that certain liquid organic substances deflect rays of 
plane polarised light, either to the right or to the left. The 
half a century later, the arrangement of atoms in space con- 
ceived by Wislicenus and formulated by Van’t Hoff and LeBel, 
and the more recent advances in the correlation of optical 
activity with chemical constitution can all be said to have 
emerged from the capital discovery of the French physicist. 
This property is of more than ordinary importance ; it concerns 
