MILK. 681 



Water 87.25 per cent 



Butter ,. :. 8.50 *' 



Caseine... 3.50 " " 



Albumen '.....-. 0.40" " 



Milk sugar ,,,. 466," " 



Mineral substances ' , 0>75 " " 



100.00 



The following table will show that there is a very variable 

 standard of pure milk, as both this and the foregoing table repre- 

 sent analyses of the best milk : — 



Water - 88.65 to 90.00 per cent 



Butter ....;.. ; 1.80 " 5.20 " " 



Caseine 8.00" 5.00 " " 



Albumen ;..... 0.30 " 0.55 " " 



Milk sugar 8.00 " 5.50 " " 



Mineral substances 0.70 " 0.80 " " 



Caseine, according to Volcker, is composed of the following 

 elements : — 



Carbon ....... .53.57 



Hydrogen '. : ;'. 7.14 



Nitrogen . .15.41 



Oxygen 22.03 



Sulphur 1.11 



Phosphorus , 0.74 



^ 100.00 



Caseine, not being in solution in the milk, is swelled up by its 

 absorption of water into a kind of thin jelly. It is not soluble in 

 water, but only in diluted hydrochloric acid and carbonate of soda. 

 It is not precipitated on boiling, but is when rennet is added at a 

 certain temperature. This precipitation by rennet is the coagula- 

 tion from which whey results. 



Fig. 845.— Vesicles of the 

 Mammary Lobules. 



Fig. 846.— Udder of a 

 Rabbit 



