THE ASSAY OF SUGAR HOUSE PRODUCTS. 



If the liquid is already in the liquid form, the above procedure may be 

 followed, or 100 c.c. of the material may be taken, and after clarification by 

 one or other of the methods given, made up to 110 c.c., filtered and the 

 polariscope reading of the filtrate taken ; then the percentage of sugar is given 



1*1 - 

 by the expression - - where D is the specific gravity of the material. 



2. In the Presence of Reducing Sugars. The sugar is obtained by the 

 Clerget process described in Chapter XXII. 



The following are irregularities in the method of analysis which are 

 discussed under separate captions, and for which correction should be made : 



1 . Volume of precipitate formed on clarification. 



2. Temperature of observation. 



3. Concentration of solution. 



4. Change in the specific rotation of the sugars before and after inversion. 

 The estimation of cane sugar as glucose is given in Chapter XXIII. 



Determination of Fibre.* In routine analysis fibre means that 

 part of the cane insoluble in water, and corresponds to the ' marc ' of the beet 

 industry ; the fibre is determined by removing the soluble constituents by 

 digestion with water or alcohol, and drying the residue to constant weight. 



Pellet 5 has shown that extractions with alcohol in a Soxhlet apparatus 

 give too high results, due to the precipitation by alcohol of bodies soluble in 

 water, and also that all bodies soluble in cold water should be first removed to 

 prevent a precipitation of albumenoids by hot water. 



Analysis of the Cane. The determination of the sugar in the 

 cane may be made by an inferential approximate method, or by more complete 

 methods. 



Inferential Method. Pass the cane under analysis through a hand mill, 

 collect and polarize the expressed juice ; then the per cent, of sugar in the cane 

 is given by the expression (100 /) $, where/ is the percent, of fibre in the 

 cane, and 8 is the per cent, of sugar in the expressed juice. This method is 

 open to the following sources of error : The juice of the cane is not uniform, 

 the first expressed juice being sweeter than that obtained later. The fibre, 

 too, is a very variable quantity, and unless the fibre be actually determined a 

 large error may be introduced. In Java it was once customary to estimate the 

 sugar percentage of the cane as '85 that of the sugar percentage of the first 

 mill juice, but this factor is very dependent on variety. 



Complete Methods. 1. Pass strips of the cane through a hand mill; 

 collect the expressed juice and crushed strips and weigh the latter at once ; 

 take as the weight of juice expressed the difference between the weight of 

 cane used and the weight of crushed strips or megass ; determine the sugar 



* See Note in Appendix, 

 475 



