168 
different contraction co-efficient, so that the solution diluted with water 
shows a different specific gravity or refractive index than that calculated 
from tables for pure sugars. 
To reduce these variations of contraction to the minimum, a concen- 
trated pure sugar solution is used as a dilutant. Results obtained with 
some cane molasses samples show the error that is introduced by the water 
dilution and also the effect of the sugar dilution. 
Ditutep Hauer WitH— 
Sample No. | Undiluted Molasses. 
Water. Sugar Sol. 
‘ | 
1 80.57 83.24 80.91 
2 72.32 72.94 Wea 
3 77.92 78.44 77.91 
4 73.92 75.34 73.81 
5 82.05 84.44 82.41 
In the undiluted form all of these can be easily read. The half dilu- 
tion with water is anywhere from .62% to 2.7% higher than undiluted 
while the half dilution with sugar solution varies from 0.0 to 0.5%. 
Tischtschenko (Z%. des Vereins Deut. Zuckerind., Feb. 1909, 103), calls 
attention to this possible error in the determination and recommends the 
use of a pure sugar solution. Von Lippman corroborates the results 
(Deut. Zuckerind., 34, 1909, 401). It therefore behooves us to use sugar 
solution in diluting our dark colored solution in preference to water. The 
formula for calculating the dry substance when using a concentrated 
sugar solution as a dilutant is: 
(A+ B) C— BD 
Sa 
in which X—% dry substance of the original sample, (A) the grams of 
— 
the original substance mixed with (B) the grams of concentrated pure 
sugar solution, (C) the % dry substance of the mixture obtained from its 
refractive index, and D= the % dry substance of the pure sugar solution 
obtained from its refractive index. The method of procedure is simply 
the preparation of a concentrated granulated sugar solution and mixing in 
a small beaker a weighed quantity of this with a weighed quantity of the 
original solution or sample, and taking refractive index of the mixture. 
