27 



dients of cheese. It is that part of the milk which forms flesh (lean 

 meat), either in the growing animal or the human being. 



Albumin differs from the casein in being in a state of complete solution 

 in the milk, and in separating out in the form of scum when the milk is 

 heated from 158" to 167° F. While it exists in comparatively small 

 amounts in normal milk, it is found in large quantities ^n the colostrum 

 (first milk after calving). 



Lactoglobulin, another albuminoid, is present in very minute traces 

 in milk. It resembles the albumin. 



Lactoprotein is present in milk to the extent of about .13 per cent. It 

 is found in solution after removing the casein, albumin and lactoglobu- 

 lin. It has been named albuminose, galactin, gelactine, etc. 



Fibrin is also claimed by Babcock to exist in milk in quantities of .1 

 per cent. 



3. Milk sugar was discovered in milk late in the seventeenth century. 

 It is a crystalline body, white in color, and has the same chemical for- 

 mula as cane sugar. It occurs only in milk, where it is found in a state 

 of perfect solution. It is not as easily soluble in water as cane sugar, 

 and possesses only a slightly sweetish taste. The amount of such sugar 

 in normal cow's milk varies from 3 to 6 per cent, with an average of 

 about 5 per cent. 



4. Milk ash, or mineral constituents, consist of potash, soda, lime, 

 magnesia and iron, vmited with phosphoric, hydrochloric, sulphuric and 

 carbonic acids. The total amount of ash is small, averaging about .75 

 of 1 per cent. The potash, lime and phosphoric acid form the largest 

 proportion of the ash. The ash, as a source of food, serves to build up 

 the bony structure of the body. 



In addition to the above principal ingredients of milk, small quantities 

 of other substances have been recognized. Citric acid has been found 

 to the extent of .1 of 1 per cent, combined with iron and magnesia. 

 Very minute quantities of urea, lecithin, kreatin, hypoxanthin, leucin 

 and tyrosin have also been recognized, formed without doubt from the 

 partial decomposition of the albumin during the process of digestion in 

 the animal body. 



Gases in small quantities, such as nitrogen, oxygen and carbonic 

 acid, also exist dissolved in the milk. 



While it not possible to give any absolute figures for the composition 

 of milk, the following will show the approximate relative proportions 

 of the several ingredients : — 



Per Cent. 



Water 87.00 



Fat, 4.00 



r Casein 2.90 



. . , Albumin, 50 



Albuminoids < , . i k i- » 



Lactoglobulin, ) ,- 



in.) 

 1, J 



[ Lactoprotein, 



Milk Sugar, 4.75 



Ash 70 



100.00 



