86 BUTTER-MAKING. 
free the fat. The contents of the bottle should be well shaken 
at once after the acid has been added. 
The bottle with its contents is then whirled about five 
minutes in a centrifugal machine at a rate depending upon the 
diameter of the machine, usually about 850 to 1000 revolutions. 
es 
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Fig. 35. Fic. 36. Fic. 37. 
Fig. 33. 
Skim-milk Whole-milk § Cream test- 9-gram cream Cream 
test-bottle. test-bottle. bottle test-bottle. test-bottle. 
Bascock TEstT-BorrueEs. 
per minute. The machine is then stopped and filled to the 
neck of the bottle with pure hot water. Distilled water is 
preferred. The bottles are then whirled two minutes, and 
hot water added again until the fat rises in the neck where it 
can be read. The bottles are then whirled again for about one 
minute. The machine is then stopped and the fat read in 
percentage direct from the bottle. By using a pair of dividers. 
