IF.A.:R,T XT. 

 ANALYSIS OF MILK AND MILK PKODUCTS. 



CHAPTER V. 



PHYSICAL DETERMINATIONS. 



The Specific Gravity of Milk Modes of Expression. 



Specific gravity is the weight of a unit of volume. The unit 

 of volume is a cubic centimetre, the unit of weight one gramme, 

 and the specific gravity of any substance is the weight of one 

 cubic centimetre in grammes. As one cubic centimetre of water 

 at 4 C. weighs one gramme, the specific gravity of water at 

 4 C. is exactly 1 ; at temperatures higher and lower than 4 C. 

 water expands, and therefore has a specific gravity less than 1. 

 Table XII. gives the specific gravity of water at different tem- 

 peratures : 



TABLE XII. SPECIFIC GRAVITY OF WATER. 



As at 4 C. one cubic centimetre of water weighs one gramme, 

 a practical method of ascertaining the specific gravity at this 

 temperature is to take the weight of any volume of the liquid 

 and to compare it with the weight of an equal bulk of water. 

 To ascertain the specific gravity at any other temperature say, 

 for example, 30 C. the weight of any volume of liquid is ascer- 

 tained and compared with the weight of water at that temperature 

 divided by the specific gravity at that temperature in the case 

 taken 0-99577. 



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