16 



BUTTER-MAKING AND COMPOSITION OF MILK 



100 94.84 



PROTEIDS (ALBUMINOIDS) 



12.53 



The proteids of milk are present partly in solution and 

 partly in suspension. They are present in a very complex 

 chemical form. Some of the chemists reckon as many as eight 

 different albuminoids or proteids in milk. Duclaux claims that 

 there are only two kinds of albuminoids, the coagulable and non- 

 coagulable casein. He has, by the use of a fine filter, been able to 

 separate the fat and the coagulable from the rest of the serum. 

 The amount of coagulable casein is claimed to vary considerably, 

 and seems to depend upon the amount of lime phosphate present. 

 The filtrate which Duclaux obtained from filtering the milk was 

 clear and colorless, which proves that the removal of the casein 

 was quite complete. In order to remove casein from milk, a 

 special filter (Chamberland) is employed. Owing to this fact, 

 we may consider the casein to be present in suspension or semi- 

 solution. Noted chemists, such as Babcock, Van Slyke, Duclaux, 

 Storch, Hammarsten, Ritthausen, and Richmond, disagree upon 

 the number of albuminoid substances found in milk, and upon the 

 chemical behavior of each. 



For all practical purposes it is safe to mention two, namely, 

 (i) casein, and (2) albumen. Those two substances, as all agree, 

 are present in milk, and constitute practically all the albuminoids 

 in milk. But after these two have been separated from milk a 

 slight precipitation can be obtained by treating the filtrate with 

 alcohol. This has been called albumose and also lactoglobulin. 

 From this resultant filtrate a very small amount of material 

 containing nitrogen can again be separated. Dr. Babcock 



