104 EXPERIMENT STATION. [Jan. 



Pakt II. Dairy and Chemical Studies. 



1. The Chemical Composition of Milk. 



B. LINDSEY. 



The larger part of milk consists of water, which contains a 

 variety of substances in suspension and solution. The sub- 

 stances largely dissolved in the water are casein and albumen, 

 milk sugar and the ash or mineral matter, which together form 

 the milk serum. 1 The fat is suspended in the milk in micro- 

 scopic globules, which are semisolid, and with the serum form 

 what is termed an emulsion. 



The multitudinous analyses of milk have shown it to vary 

 widely in composition, depending upon the breed and individ- 

 uality of the cow, stage of lactation and weather conditions. 

 Food, as a rule, has little effect in permanently changing the 

 proportions of the several ingredients. Numerous authorities 

 state that 100 pounds of milk of average quality should contain 

 the following amounts of the different ingredients : — 



Pounds in 100, or 

 Percentage. 



Water, 87.00 



Fat, 4.00 



A1 , . •! ( Casein, ...... 3.00 



Albuminoids •> 



( Albumen, ...... .50 



Milk sugar, 4.80 



Ash, .70 



100.00 



The term « ' total solids " is meant to include all of the in- 

 gredients excepting water. For ordinary purposes the chem- 



i Tli.it portion of the casein which can be removed by filtration through filter paper is 

 not generally included in normal serum. 



