FROZEN MILK. 399 



TABLE CXXXVL COMPOSITION OF FROZEN MILK. 



As all these samples were taken from churns in which milk 

 was brought up to London, the percentage of ice may be taken 

 as indicating roughly the temperature below freezing point to 

 which the milk was exposed, the time of exposure to the low 

 temperature having been approximately the same in all cases. 

 It appears that the lower the temperature to which milk is 

 exposed the more dilute will be the ice after melting. 



Composition of Melted Frozen Milk. The difference in 

 composition between frozen and unfrozen milk may have some 

 importance, should samples be taken under the " Sale of Food 

 and Drugs Act," in very cold weather ; should an excessive 

 proportion of ice be present in the portion sold to the inspector 

 the sample may, though originally genuine, have the composition 

 of watered milk. 



Vieth has recorded an interesting experiment on the freezing 

 of milk : Two gallons of milk were exposed to a temperature of 

 10 C. (14 F.) for three hours ; longer time than this did not 

 render any more milk solid. Ice was formed on the bottom and 

 sides of the vessel employed to contain the milk and a funnel- 

 shaped cavity in the centre was filled with liquid. The ice was 

 found to consist of two layers, one of cream, and the other of 

 skim milk ; these were separated as completely as possible and 

 the liquid portion also poured off. 



The results of analysis were : 



TABLE CXXXVIL COMPOSITION OF FROZEN MILK (Vieth). 



