No. 4.] MILK AND CREAM. 349 



substances to a considerable extent dissolved in the water are 

 casein, albumen, milk sugar and the ashy matters. This 

 solution forms the so-called milk serum. The fat exists in 

 the milk in suspension, in the form of very minute micro- 

 scopic globules. They are semi-solid and form with the 

 serum what is termed an emulsion. 



1. Milk Fat. — The fat globules in milk vary in size from 

 .0016 of a millimeter to .01 of a millimeter (^^-^ to i^-q 

 of an inch), e. (/., microscopically small. The smaller the 

 more numerous they are. As a rule the globules in the milk 

 of the Jersey and Guernsey cows are larger in size than those 

 in the milk produced by Holsteins or Ayrshires. The glob- 

 ules are largest in the milk of newly calved cows. The 

 percentage of fat in the milk product of the United States 

 may be said to vary between 2.25 and 8 per cent with a 

 probable average of 4 per cent. 



Milk fat contains two kinds of fat, the so-called non- vola- 

 tile and volatile fats. Neutral non-volatile fat is a combi na- 

 tion of glycerine with fatty acids, such as the palmitic, stearic 

 and oleic acids. There is about 92 per cent of non-volatile 

 and 8 per cent of volatile fats in the fat of milk. Duclaix 

 has estimated butter fat to be composed of the following sep- 

 arate fats : — 



Per Cent. 



Palmitin, stearin, olein, with traces of myristin and 



butin, 91.50 



Butyrin, 4.20 



Capronin, 2.50 



Caprylin, eaprinin and traces of lanrin, . . . 1 . 80 



100.00 



Butter consists largely of milk fat (85 per cent) and hence 

 the value of milk for butter depends upon the quantity of fat 

 it contains. 



2. Milk Albuminoids {Nitrogenous Matter). — The albu- 

 minoid or nitrogenous portion of milk contains five distinct 

 substances, namely, casein, albumin, lactoglobulin, lactopro- 

 tein and fibrin. 



Casein forms about 80 per cent of the total albuminoids. 

 It exists in the milk, combined with lime in a semi-dissolved 

 condition, and possesses a certain amount of opacity (lack 



