18 Testing Milk and Its Products. 



The ash content of normal cow's milk varies but lit- 

 tle, as the rule only between .6 and .8 per cent., with an 

 average of .7 per cent. Milk with a high fat content 

 generally contains about .8 per cent, of ash; strippers' 

 milk always has a high ash content, at times even ex- 

 ceeding one per cent. Ordinarily, the mineral constitu- 

 ents are least liable to variations of any of the com- 

 ponents of the milk. 



31. Other components. Besides the milk constitu- 

 ents enumerated and described in the preceding pages, 

 normal milk contains a number of substances which are 

 present in but small quantities and have only scientific 

 interest, such as the milk gases (carbonic acid, oxygen, 

 nitrogen), citric acid, lecithin, eholesterin, urea, hypo- 

 xanthin, lactoehrome, etc. 



22. Average composition. The average percentage 

 composition of cow's milk will be seen from Table I in 

 the Appendix. The following statement shows the lim- 

 its within which the components of normal American 

 cows' milk are likely to come: 



Minimum. Maximum,. Average. 



Water 82.0 per et. 90.0 per ct. 87.4 per et. 



Pat 2.3 7.8 3.7 



Casein and albvonen 2.5 4.6 3.2 



Milk sugar 3..5 6.0 5.0 



Ash .6 .9 .7 



23. Colostrum milk. The liquid secreted directly 

 after parturition is known as colostrum milk or biest- 

 ings. It is a thick, yellowish, viscous liquid; its high 

 contents of albumen and ash are characteristic, and also 

 its low content of milk sugar. Owing to the large quan- 

 tity of albumen which colostrum contains, it will coagu- 



