ANALYTIC PROCESSES 



Specific Gravity. — The sp. gr. of milk rises 

 gradually for some time after it has been drawn, 

 and the determination is to be made only after 

 this action has ceased. This wiU require about 

 five hours after the milk is drawn, if it has been 

 kept 15°, but at a higher temperature it will be 

 necessary to allow at least twelve hours. For 

 all other determinations the milk must be ana- 

 lyzed as soon as possible. The following figures, 

 published by Bevan, show that a considerable 

 loss in total solids may occur in twenty-foxu- 

 hours : 



Evaporated immediately . . . 

 Evaporated after 24 hours. 

 Evaporated after 48 hours, 

 Evaporated after 120 hours. 



The decomposition is very irregular, and it is 

 not possible to determine, by estimation of the 

 lactic acid or other products, the original compo- 

 sition of the milk. 



Air-bubbles are held rather tenaciously by milk, 

 and care must be taken in mixing, preparatory 

 to taking the sp. gr., to avoid as far as possible 



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