i66 



MODERN METHODS OF TESTING MILK 



they allow the hot milk to 

 filter rapidly but retain the 

 dirt suspended in the milk. 

 Centrifugal test for dirt. 

 A small centrifugal ma- 

 chine that is made to run at 

 a higher speed than the Bab- 

 cock testers is used. A form 

 of hand-centrifuge is shown 

 in Fig. 41. Special gradu- 

 ated tubes (Fig. 42) are 

 made to use in this. The 

 milk to be tested is stirred 

 thoroughly, the tube is filled 

 to the highest mark, placed 

 in the pocket of the centri- 

 fuge and whirled several 

 minutes. The sediment col- 



FIG. 41 HAND-CENTRIFUGE 

 FOR SEDIMENTATION WORK 



FIG. 42 TUBE FOR 

 SEDIMENTATION WORK 



FIG. 43 BAUSCH & LOME 



ELECTRIC CENTRIFUGE 

 Speed, 1,000 revolutions per minute 



