966 Proceedings of Royal Society of Edinburgh. [sess. 
different experimenters are considered, these varying for the same 
concentration by as much as twenty per cent. 
It will thus be seen that molecular weight determinations by 
the boiling point method have been set on a much more satis- 
factory basis, and at the same time one giving better results. It 
is claimed, therefore, for the method adopted — namely, the deter- 
mination of elevation per gramme equivalent by adding salt to a 
solution rather than to the solvent — that it gives to boiling point 
work on aqueous solutions greatly increased accuracy, whether we 
view it from the standpoint of values obtained for C, or from 
that of molecular weight determinations. 
It may also he noted that as the manner in which the ionization 
coefficients were obtained and the formula used in calculating 
values of C were based, each on the dissociation theory, conse- 
quently the theory has been put to a somewhat severe test ; and 
as the results agree so fully with theory, it has been entirely 
favourable. 
The research was carried out at the Physical Laboratory of the 
Edinburgh University, and is to be continued. 
( Issued separately November 4 , 1905 . 
