MILK. 145 



agulated. To determine the quantity of protein subtract 

 the sum of fats, sugar, and ash from the total solids. 



331. Examine with the microscope a drop of milk 

 under a cover-glass. 



332. Destroy the emulsion by adding 10 cubic centi- 

 meters of concentrated sulphuric acid to an equal volume 

 of milk. Let it stand, and the fat rises to the top in large 

 globules. The separation is complete in a few minutes if 

 a centrifuge is used. The volume of the fat can be better 

 seen by using a narrow-necked flask and, after mixing with 

 the acid, nearly filling with warm water. 



333. Fill a 100-cubic-centimeter graduated cylinder 

 to the upper mark with milk and let it stand twenty-four 

 hours. There should be 10 or 15 cubic centimeters of 

 cream. 



334. To DETERMINE THE PERCENTAGE OF LACTOSE 

 IN MILK. Dilute 20 cubic centimeters of milk to 400 

 cubic centimeters with water. Drop in acetic acid slowly 

 until it coagulates; then pass carbon dioxid gas into the 

 liquid fifteen minutes and let it stand until it settles clear. 

 Filter and wash; coagulate the albumin and globulin in 

 the filtrate by boiling. Filter, wash, and use the filtrate or 

 a part of it for the sugar-determination by Fehling's solu- 

 tion as in the determination of glucose (Experiment 33). 

 For every 10 cubic centimeters of the solution which is 

 decolorized 0.067 gramme of lactose is present. 



335. BABCOCK'S METHOD FOB THE DETERMINATION OF FAT 

 IN MILK OK CREAM. When sufficient milk is available, 17.6 cubic 

 centimeters may be taken for each determination. The bottles in 

 which it is treated have a special scale etched upon the rather long 

 neck. 



Mix the milk thoroughly by pouring it several times from 

 one vessel to another. With a pipette graduated at 17.6 cubic 



