MILK 



61 



In 



2. iJabcock's Method. 

 1 890 Dr. S. M. Babcock l recommended the following 



method for determining volu metrically the percentage of fat in 

 milk. It is based upon the treatment of a known quantity of 

 milk with a definite volume of concentrated sulphuric acid (sp. gr. 

 1*82-1 '83) in a glass test-bottle of special shape. This causes 

 the casein to dissolve,' and after the sample has been whirled in 

 the centrifuge the test-bottle is filled almost full with boiling 

 water and again centrifuged. When the test-bottle is taken 



FIG. 24. Method of Reading the Tester. 



from the centrifuge, the height of the column of fat can be 

 read off on the graduated neck. The apparatus is shown 

 in Fig. 25, and a sketch of the test-bottle in Fig. 26. 



The actual test is carried out as follows : The well-mixed 

 milk is measured in the special 17'6 c.c. pipette, and then run 

 into the test-bottle. With the help of a small glass cylinder 

 17'5 c.c. of sulphuric acid (ordinary commercial acid, sp. gr. 

 1 '82-1 '83), are measured out and poured into the test-bottle, 

 which is held obliquely so that the acid runs to the bottom and 



1 Seventh Ann. Rep. oftheAgr. Expt. Stat. of the University of Wisconsin, 

 1889-1890, p. 98. 



