MILK AND ITS PRODUCTS 137 



Apparatus. This consists essentially of the following 

 parts : A, Babcock tester ; B, milk bottle ; C, cream bottle ; 

 D, skim-milk bottle ; E, pipette or milk measure ; F, acid 

 measures; G, cream scales; H, mixing cans; I, dividers. 



A. Babcock Tester. This machine, shown in Fig. 29, 

 consists of a revolving wheel placed in a horizontal posi- 

 tion and provided with swinging pockets for the bottles. 

 This wheel is rotated by means of a worm wheel (lower 

 machine) at the top of the" tester. When the tester stops 

 the pockets hang down allowing the bottles to stand up. 

 As the wheel begins rotating the pockets move out causing 

 the bottles to assume a horizontal position. The wheel is 

 enclosed in a cast iron frame provided with a cover. 



B. Milk Bottle. This has a neck graduated to ten 

 large divisions, each of which reads one per cent. Each 

 large division is subdivided into five smaller ones, 

 making each subdivision read .2%. The contents of the 

 neck from the zero mark to the 10% mark is equivalent to 

 two cubic centimeters. Since the Babcock test does not 

 give the percentage of fat by volume but by weight, the 

 10% scale on the neck of the bottle will, therefore, hold 

 1.8 grams of fat. In other words, if the scale were filled 

 with water it would hold two grams ; but fat being only 

 .9 as heavy, 2 cubic centimeters of it would weigh nine- 

 tenths of two grams or 1.8 grams. This is exactly 10% 

 of 1 8 grams, the weight of the sample used for testing. 

 A milk bottle is shown in Fig. 30. 



C. Cream Bottles. These are graduated from 30% to 

 55%. A 30% bottle is shown in Fig. 31. Since cream 

 usually tests more than 30%, the sample must be divided 

 wher. the 30% bottles are used. 



