1906-7.] Mixed Solutions of Optically- Active Substances. 
175 
Experimental. 
The properties of the solutions which were chosen for measurement 
were electrical conductivity, viscosity, and, as incidental to the viscosity 
determinations, density. 
The viscosity measurements were made with the apparatus described 
in detail in a recently published paper * on the Viscosity of Solutions. It 
may be mentioned here that what is experimentally determined is the ratio, 
rjlrj 0 , of the viscosity of the solution to the viscosity of the solvent at the 
temperature of experiment. This ratio may be taken to be accurate to less 
than 1 in 1000. 
The density determinations were made in the usual manner by means 
of an Ostwald-Sprengel pycnometer ; a high degree of accuracy was not 
aimed at in the density determinations. 
The electric conductivity of the solutions was also measured in the 
usual alternating-current method with telephone and Wheatstone bridge. 
Every measurement given in the tables is the mean of several concordant 
determinations, made, as a rule, on duplicate solutions. In some cases the 
duplicate solutions were made up from different samples of the substances. 
Two pairs of optically-active stereoisomers were used, the normal 
potassium tartrates and the tartar emetics ; for the sake of comparison, 
potassium racemate and racemic emetic were also included. 
The independent optically-active substance was cane sugar, but in one 
additional set of experiments maltose was employed ; the reason for 
selecting maltose will be given later on. 
Water was the solvent in all cases. 
The ^-tartaric acid was made from racemic acid by resolution with 
cinchonin. For the potassium tartrate solutions the three acids were 
converted into the potassium hydrogen salts, which were then repeatedly 
recrystallised. Weighed quantities of the dry salt were exactly neutralised 
with pure potassium hydroxide, and the solutions then were made up to the 
requisite volume. 
The c£-tartar emetic was a specimen of commercial pure emetic which 
was recrystallised several times. 
The ^-emetic and r-emetic were made from the corresponding potassium 
hydrogen salts by boiling up with pure antimonious oxide and much water 
for two to three hours; the liquid was then filtered and allowed to 
crystallise. The product was then recrystallised several times. Owing to 
* Trans. Roy. Soc. Edin ., 45, p. 397, 1906. 
