106 Milk and Its Products 



chine is stopped, and the bottles are filled with 

 warm water to the bottom of the neck. They are 

 then whirled a second time for two minutes, when 

 water is again added up to about the 8 per cent 

 mark on the- neck of the bottle, after 

 which they are given a whirl for one min- 

 ute. The bottles are then taken out and 

 as -rapidly as possible. 



Reading. The reading should be taken 

 at a temperature between 110 and 140 

 F., at which temperatures the fat will be 

 completely fluid. The test should be made 

 in a room at a temperature not less than 

 70 F., or if the room is much colder 

 some means should be taken to prevent 

 the bottles from becoming cool until all are 

 read. Much skill and facility can be 

 attained by practice in reading the bottles 

 ""^rapidly and accurately. In reading the 

 bottles, the .reading should be made as 

 shown in the diagram, the lower reading 

 Fig. is. Dia- from the extreme lower curved surface 

 of an Babcock (a, Fig. 15), and the upper reading from 

 thl reading the extreme top of the column of fat, 



be^ (6, not c, Fig. 15), the difference between 



tween the , . . . _ 



points a-6, the lower and upper reading giving the 

 percentage of fat. The reason for read- 

 ing in this way is that a small amount of residual 

 fat is left mixed with the other fluids in the bottle. 

 This is composed of the smaller globules of fat, and 

 the amount is practically uniform, and has been 



