THE BABCOCK TEST 37 



4. Mixing milk and acid. The milk and acid 

 having been placed in the test bottle, are now 

 mixed by taking the bottle by the neck and 

 giving it a rotary motion. The acid immediately 

 dissolves the curd, the bottle becomes hot and the 

 contents turn black. 



5. Whirling and filling bottles. The bottles 

 are now placed in the machine and whirled for 

 five minutes. They are then filled up to the 

 bottom of the neck with hot water, using either 

 the acid measure or the pipette for this purpose. 

 If hard water is used the carbonates in it must 

 be broken up by adding to it a few drops of 

 acid before filling the bottles, otherwise the car- 

 bonates in the water may cause a foam to appear 

 on the fat and spoil the reading. Only a few 

 drops of acid should be used, and to prevent 

 accident these should be dropped from the acid 

 measure and not from the bottle. Great care is 

 necessary in handling this acid. 



The bottles are whirled a second time for one 

 or two minutes, the fat is then brought up into 

 the neck by adding a few more drops of hot 

 water, the bottles returned to the tester and 

 whirled a third time for a minute or two, when 

 they are taken out and placed in a water bath 

 having a temperature of 120-140 degrees P., 

 where the fat column should be submerged for 

 four or five minutes. 



