278 



THE COMPLETE GRAZIER. 



substance the blood is, and what is the nature of the materials from 

 which the mammary gland has to elaborate the milk. 



The average percentage composition of the whole milk of the cow is 

 contrasted with that of skim-milk in the following table : 



Whole Milk. Skim-Milk. 



87-0 . 90-0 



4-0 3-7 



Water . 



Albuminoids 



Milk-Sugar 



Fat 



Ash 



4-o 

 3-7 

 0-7 



100-0 



4-8 

 0-8 

 0.7 



100-0 



The albuminoids, or nitrogenous compounds, are casein and albumin, 

 the latter in ordinaiy cow's milk constituting not more than one-ninth 

 of the total albuminoids ; the ash consists of lime, potash, soda, 

 magnesia, and iron, with phosphoric acid and chlorine. As may be 

 inferred from a comparison of the foregoing tables, most of the fat is 

 removed in the cream ; theoretically all the fat should be removable in 

 this way, and in the most efficient centrifugal separator the residue of 

 fat which is left in the skim-milk is as little as 0'2 per cent. It is 

 further evident that the liquid part of the milk, after separation of the 

 fat globules, still retains all the milk- sugar and most of the albuminoids. 

 It is worthy of note, too, that skim-milk contains the same percentage 

 of water as the serum of blood. 



The subjoined tables, quoted after Duclaux, throw additional light 

 on the subject of the composition of cow's milk : 



COMPOSITION OF COW'S MILK AND OF SKIM-MILK. 



PERCENTAGES OF DRY MATTER IN THE MILK OF THE SAME COW 

 AT DIFFERENT DATES. 



1 The casein "in solution" represents albumin. 



