52 Milk and lis Products. 



paratus is different from the Babcock test, a much 

 higher speed of whirling is used, a smaller sample 

 of milk is taken, and the fat is read in a solid 

 instead of a liquid form. 



DETAILS OF THE BABCOCK TEST. 



The apparatus used in testing milk by the Bab- 

 cock method consists of a centrifugal machine, three 

 pieces of glassAvare and commercial sulphuric acid. 



The centrifugal machine. — Many forms of centri- 

 fugal machines are in use, almost every manufacturer 

 having his own particular style. It is essential that 

 the centrifugal should be substantially made ; that it 

 should run smoothly and steadily, either loaded or 

 empty, and that it should be capable of developing a 

 speed of 900 revolutions per minute, with a wheel 

 20 inches in diameter. The centrifugals so made 

 may be driven either by hand or steam power. In 

 the hand- power machines, the motion is transmitted 

 both by belts and by friction cogs ; in the latter 

 case it is essential that care be taken to prevent 

 loss of motion through the friction cogs becoming 

 worn. 



In the centrifugals driven by steam turbines, or 

 jets of steam delivered against the circumference of 

 the revolving wheel, it is much better that the 

 steam be applied at some little distance from the 

 revolving bottles, otherwise too great a degree of 

 heat may be developed in the machine. Woll has 

 shown* that, in those steam turbines in which 



♦Hoard's Dairjinan, March 9, 1900: vol. 31, p. 75. 



