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. 



Sample No. 



Undiluted Molasses. 



Diluted Half With — 



Water. 



Sugar Sol. 



1 

 2 

 3 

 4 

 5 



80 . 57 

 72.32 

 77.92 

 73.92 

 82.05 



83.24 

 72.94 



78 . 44 

 75 . 34 

 84.44 



80.91 

 72.21 

 77.91 

 73.81 

 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 0.3%. 



Tischtschenko (Z. des Vereins Dent. 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 



X = 



A 



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. 



