30 PROFITABLE DAIRYING 



IV. To Determine the Ash and Sugar Content of Milk 



The filtrate obtained from Problem III will contain 

 both the ash and the sugar. 



1. Evaporate to dryness over a water bath. The gray 

 residue will be both the sugar and the ash. 



2. The residue can be burned over a free flame until 

 the sugar is burned up. Ash will remain. 



The per cent of milk sugar can be approximately 

 determined by carefully obtaining the per cent of the 

 other constituents in milk, such as water, fat, casein, 

 albumen, and ash, adding them all together and sub- 

 tracting the sum from 100. 



Note: A qualitative test to show the presence of sugar can 

 be made by using some of the filtrate. Add about 20 to 25 

 drops of the filtrate slowly to about 5 c.c. of hot Pehling's 

 solution. After boiling a red precipitate will appear. This 

 indicates the presence of sugar. 



