524 CHAPTER XXV 



The values of x and y can then be found by solving the two simple simul- 

 taneous equations. 



It must be remembered, however, that in cane products unfermentable 

 reducing sugars occur, so that only approximate results can be obtained. 



The Simultaneous Determination of Cane Sugar and Raffinose. — The 



official German method due to Creydt^^ is as follows : — 



The direct reading is taken at 20° C. ^y 



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 — Sugar per cent. „ 



Raffinose per cent. 



o-8i 

 A -S 



1-54 

 Pieraert's^* process is as follows : — 



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

 give the direct reading. Fifty 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 

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

 taken. Then if x and 3/ are quantities of cane sugar and of hydrated raffinose 

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



X = g-287« — 18-316 



y = 3-659^ +11-6526 



The Simultaneous Determination of Cane Sugar, Invert Sugar, and Raf- 

 finose. — The following scheme is due to \A'^ortmann^^ : — 



The reducing sugars are determined and calculated according to the 



formula R — ^^^' , 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 : — 



0-9598^ — 1-855 — 0-277i? 



Per cent, cane sugar = 

 Per cent, raffinose = 



1-5648 

 A — S xo-3io3A^ 



i-»5 

 where A and B are the direct and invert readings. 



Determination of Fibre in Cane and Bagasse. — Fibre in cane sugar-house 

 work refers to everything insoluble in water. It is therefore to be carefully 

 distinguished from the " Crude fibre " of plant anatysis or from its chief 

 constituent, cellulose. Methods for its determination are given below, the 

 remarks under " Determination of Sugar in Cane " referring to comminution 

 being equally applicable here. 



I. Differential Method. — Dry the material and estimate the fibre by 

 difference : — 



Fibre per cent. = 100 — water per cent. — soluble solids per cent. 



