38 ANALYTICAL PROCESSES. 



1.42 sp. gr. and adding to the solution an equal bulk 

 of water. 



60 c. c. of the milk are placed in a 100 c. c. flask 

 and I c. c. of the mercuric solution added. The flask 

 is filled to the mark with water, well shaken and the 

 liquid filtered through, a dry filter. The filtrate, which 

 will be perfectly clear, may be examined in the polar- 

 imeter. Several readings should be made and the 

 average taken. 



It is to be noted that the actual volume of the sugar 

 containing solutionis 100 c. c, less the space occupied 

 by the precipitated proteids and fat. The volume of 

 fat is found by multiplying the weight in grams by 

 1.075 and the proteids by multiplying the weight by .8 



For example : — 

 Sp. Gr. of milk 1030, Fat 4 per cent, Proteids 4 per cent. 

 Milk taken = 60 X i-03 = 61.80 gms. 

 The weight of fat = 4 per cent of 5i.8o = 2,47 gms. 

 The weight of proteids = 4 per cent, of 61.80 = 2.47 gms. 

 The volume of fat = 2.47 X i-"75 = 2.65 c. c. 

 The volume of proteids = 2.47 X .8 = 1.97 c. c. 

 The bulk of the sugar containing liquid is therefore 

 100 — (2.65 + 1.97) = 95.38 c. c. 



In order to avoid the calculation involved in taking 

 60 c. c. of the milk as given above, an amount may be 

 employed which is a simple multiple of the standard 

 quantity to be used in the polarimeter at hand- 

 Thus, for instruments adjusted so that 16.19 grams of 

 sucrose (20.56 grams of milk sugar) in 100 c. c. of the 



