350 BOARD OF AGRICULTURE. [Pub. Doc. 



of transparency). The proportions in which the casein and 

 lime exist in combination are 100 parts of the former to 1.55 

 of the latter. 



Casein forms the chief constituent of the milk curd, which 

 separates out when the milk becomes sour. Casein is one 

 of the two chief ingredients 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 com- 

 plete 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 in 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 

 of 1 per cent. It is found in solution after removing the 

 casein, albumin and lactoglobulin. It has been named albu- 

 minose, galactin, gelactine, etc. 



Fibrin is also claimed by Babcock to exist in milk in 

 quantities of .1 of 1 per cent. 



3. Milk sugar was discovered in milk late in the seven- 

 teenth century. It is a crystalline body, white in color, and 

 has the same chemical formula 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 aver- 

 age of about 5 per cent. 



4. Milk ash, or mineral constituents, consists of potash, 

 soda, lime, magnesia and iron, united 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 pro- 

 portion 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. 



