40 MODERN METHODS OF TESTING MILK 



which no dampers are provided in the cover, the steam 

 testers may heat the fat too high. For use on farms, 

 hand-testers are available. It is always necessary that 



FIG. I/ ELECTRIC CENTRIFUGAL MACHINE OF LATEST DESIGN FOR 

 USE IN BABCOCK TEST 



Capable of unusually high speed safe, accurate and convenient. Made 

 by International Instrument Co. Cambridge, Mass. 



the tester should be securely fastened to a firm founda- 

 tion and so set that the revolving disc is level. The 

 centrifugal should run smoothly, without jar or trem- 

 ble, when going at full speed. 



Estimating speed of centrifugal tester. In order 

 to cause separation of the most fat possible, the cen- 

 trifugal disc must move at a sufficient speed. The re- 

 quired number of revolutions depends upon the diame- 

 ter of the disc, to the edge of which the test-bottles are 



