THE OPTICAL ASSAY OF SUGARS. 



The difference between direct polarization and the polarization due [to 

 Clerget's process is the polarization of the dextrose and levulose in the 

 mixture ; the dextrose and levulose are then separated according to the 

 equations above. 



The simultaneous Determination of Cane Sugar and 

 Raffinose. The official German method due to Creydt 26 is as follows : 



The direct reading is taken at 20 C. 



The material is inverted according to the official Clerget process. 

 Let A = direct reading, B = reading after inversion, c = algebraic 

 difference between A and B. 



Then C- 



Sugar per cent. = 



Raffinose per cent. = 



81 

 A- 8 



1-54 



Pieraert's process is as follows 27 : 



10 grms. of material are dissolved in 100 c.c. ; this solution serves to give 

 the direct reading. 50 c.c. of this solution are transferred to a 100 c.c. flask, 

 to which are added 10 c.c. of a 20 per cent, solution of citric acid, and the 

 mixture boiled for 15 minutes in a flask to which is attached a reflux con- 

 denser ; after making up to 100 c.c. and cooling, the inverted reading is 

 taken. Then if x and y are quantities of cane sugar and of hydrated raffinose 

 in 100 c.c. of solution, and a and I are the readings before and after inversion, 



x 9-287- 18-3113 



y = 3-6590 + 11-6523 



The simultaneous Determination of Cane Sugar, 

 Invert Sugar, and Raffinose. The following scheme is due to 

 Wortmann 28 : 



The reducing sugars are determined under Clerget's process, and calculated 

 according to the formula 



= 



q 



R being the per cent, reducing sugars, C the weight of copper, and q the 

 quantity of material used. 



The direct and invert readings are then obtained according to the official 

 German method. 



Then 



"9598^ - 1-85 J 277* 



Per cent, cane sugar = 



Per cent, raffinose = 



1-5648 

 A ~ 8 + ' 



1-85 

 where A and JB are the direct and invert readings. 



457 



