THE CHEMICAL CONSTITUENTS OF MILK 315 



coagulation of the albumin. The formation of clots is most 

 easily overcome by adding a considerable amount of sugar. 

 The product is then known as " sweetened condensed milk." 

 An unsweetened variety is also prepared by evaporating at 

 a lower temperature. It is not, as a rule, so highly concen- 

 trated. From about one-half to two-thirds of the original 

 water is generally evaporated, i.e. the product contains from 

 two to three times the percentage of all the solids present *in 

 the original milk. The relative proportions of the several 

 constituents are not affected by the process of concentration. 



The following analyses l show the average composition of 

 unsophisticated condensed milk : 



Condensed milk. 

 Sweetened. Unsweetened. 

 Per cent. Per cent. 



7I-84 _ 

 8-10 

 8-66 



lOO'OO 



Concentration (times) . . . 2-3 2*2 



Colostrum. -The first milk produced by cows after parturi- 

 tion differs markedly in composition and properties from 

 ordinary milk. It is known as colostrum or " beastings." 

 Colostrum exhibits a distinct yellow colour, a peculiar, revolt- 

 ing odour, a saltish taste, and has a feeble acid reaction. 

 It is unfit for human consumption, and is useless for churning 

 or cheese making. It is, however, very suitable for the newly 

 born calves, as it is very nutritious and has a laxative effect 

 which opens the bowels. The calves should, therefore, be 

 allowed to suck for three or four days, by which time the milk 

 has generally assumed its normal character. 



Viewed under the microscope, colostrum is seen to contain 

 numerous granular bodies called colostrum corpuscles. They 

 are much larger than the ordinary fat globules, and resemble 

 the white corpuscles of blood in appearance. 



1 Leach, "Food Inspection, an Analysis." 



