l6 A DAIRY LABORATORY GUIDE 



EXERCISE III 

 BABCOCK TEST 



1. Test in duplicate a sample of whole milk, 



skimmed milk and cream. Test the skimmed 

 milk in the same way that the whole milk is 

 tested. 



Why is cream taken by weight instead of by 

 volume? 



Why are 9 grams used instead of 18 grams? 



When 9 grams of cream are tested in an 18- 

 gram bottle, what correction has to be made 

 in the result and why? 



2. Retest the cream and skimmed milk. Add acid 



to the skimmed milk about one-fourth of an 

 inch above the mark on the acid measure and 

 whirl ten minutes the first time, two minutes 

 the second time and one minute the third 

 time. 



In retesting the cream do not add water, and 

 use one-half the usual amount of acid. 



In order to save time the cream and skimmed 

 milk may be whirled together. 



Explain fully the object of using extra acid and 

 whirling an extra length cf time in testing 

 skimmed milk. 



Record carefully any difference in the appear- 

 ance of the fat column of the cream in ex- 

 periments I and 2. 



What should be the appearance of an ideal fat 

 column in a completed Babcock test ? 



