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. 



21. 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, cholesterin, urea, hypo- 

 xanthin, lactochrome, 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 ct. 90.0 per ct. 87.4 per ct. 



Fat 2.3 7.8 3.7 



Casein and albumen ___ 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- 



