228 Journal of the Asiatic Society of Bengal. [N.S., XVII, 
to complete racemisation, as both antipodes have the saine 
mechanical stability. 
However, all these suggestions must be considered hypo- 
theses, which are sometimes useful, but none the less quite 
arbitrary. 
Frankland expressed the position quite rightly in 1913, 
when he stated ‘it appears that there does not exist at the 
present time any criterion by which the relation between the 
configuration of an optically active compound and that of its 
derivative can be decisively ascertained.” 
e most recent researches carried out by Senter and his 
collaborators from 1915 onwards further show the utter in- 
adequacy of these so-called ‘‘explanations.’’ which are based 
solely on the réle which the reagent plays in these reactions. 
e phenomenon is much more complicated than was thought 
at first. 
The role which the solvent plays on the sign of rotation 
of an optically active product first discovered in 1915 by 
Senter and Drew opened up a new chapter in the study 
acetonitrile, and the lower aliphatic alcohols, the amino acid 
has the same sign as the original chloroacid. These results are 
given in the following table :— 
Senter and Drew T. 1916, 109, 1092. 
Sign of chloro- Specific rotation Comparison of 
id taken. 
Solvent. of amino acid sign of product 
formed. and chloro-acid. 
or aig NH; ie 1— — 20° —90° Same si 
ater .. .- i + Change of sign. 
CH;0H .. sik d— d (very small) Same sign. 
H  d~ +24 
C;H;OH (n) d— +8 ‘ 
C2:H,OH (iso) . d— +4 or 
C,H OH (n) oe 1— +3? Change of sign. 
C,H);OH (n) d— —73 = * 
C,H,CH,OH mo 1— +2 5 
on ea d— —16 ” 
: + i d— - +6 Same sign. 
CsH;CN .. aos d— —4 Change of sign. 
chloro-acid. But there are also important differences which 
will undoubtedly prove of great value in elucidating the 
