is used in referring to the nitrogenous Constituents 'taken 

 as a whole. The amount of casein in average cow's milk 

 varies from 2 to 4 per cent and the albumin from 0.5 to 

 0.8 per cent. 



Sugar. Milk sugar, or lactose, belongs to a group known 

 as carbohydrates and is a white substance less sweet in 

 taste than cane sugar. Milk sugar is broken up into lactic 

 acid by the action of bacteria, this bringing about the sour- 

 ing of milk. Milk sugar is in solution in the water of the 

 milk and is present to the extent of from 3.5 to 6 per cent. 



Ash. The ash, or the mineral part of milk, exists to the 

 amount of about 0.75 per cent and consists largely of the 

 chlorids and phosphates of sodium, potassium, magnesium, 

 and calcium. 



AVERAGE CHEMICAL COMPOSITION, 



The table below gives the average of more than 5,00*0 

 analyses of milk at the New York State Agricultural Exper- 

 iment Station, Geneva: 



Per cent. 



Water 87. 1 



Total solids ' 12. 9 



Fat 3.9 



Casein 2. 5 



Albumin 7 



Sugar 5.1 



Ash. : 7 



TESTING FOR FAT. 



In the following remarks on the testing of milk and 

 cream the aim will be to present the subject in such man- 

 ner that it may be followed by those who have had neither 

 chemical training nor a course of any sort in milk testing. 

 To those who have had such training the following pages 

 will doubtless appear very elementary and overburdened 

 with detail. 



TESTING MILK FOR FAT. 



Preparing the sample for testing. As before mentioned, 

 fat is not in solution in milk, but is in an emulsion of very 

 fine globules. These, being lighter than the surrounding 

 serum, tend to rise, carrying with them some of the other 

 solids, resulting in the familiar creaming of milk. Before 



