The Bahcock Test Glassware. 



53 



steam is introduced into the bottle chamber or 

 where the cover fits so tightly that no cold air 

 enters the chamber during the whirling ; the bottles 

 are often heated to such a degree that the reading 

 is made too large because of the expansion of the 

 fat at the high temperature. The fat should be read 

 at a temperature of 110° F., 

 but up to 140° F. the expan- 

 sion is not sufficient to cause 

 material error. When, how- 

 ever, the temperature rises to 

 200° F. or thereabout; as fre- 

 quently occurs under the con- 

 ditions named above, the error 

 due to the expan- 

 sion of the fat may 

 amount to .15 to 

 .3 per cent. In all 

 such cases the bot- 

 tles should be al- 

 lowed to cool to at 

 least 140° F. before 

 reading. Those cen- 

 trifugals are most 

 satisfactory in which provision is made for the bottles 

 to assume a perfectly horizontal position when in mo- 

 tion and a perfectly perpendicular one when at rest. 

 The gJassivare. — The glassware consists of a flask 

 or test bottle in which the determination is made, 

 a graduated pipette for measuring the milk, and a 

 short graduated glass cylinder for measuring the 



Fig. 4. Steam turbine centrifugal for 

 Babeock test. (See opposite page.) 



