TESTING 251 



skimmed-milk, as it flows from the separator, or in the 

 case of buttermilk, as it is drawn from the churn. A drip 

 sample is often the most convenient method of obtaining 

 skimmed-milk to test. This is taken as follows : a small 

 pail is hung under a hole in the lower side of the skimmed- 

 milk spout of the separator; a portion of the skimmed- 

 milk will drip through this hole into the pail. 



226. Testing skimmed-milk and buttermilk. — The 

 testing of these products is similar to that of testing whole 

 milk, with the exception of steps 3 and 6. In testing 

 whole milk, a measure of 17.5 c.c. of acid is used as noted 

 in step 3, while in testing skimmed and buttermilk about 

 2 c.c. more acid is necessary, because there is a greater 

 amout of solids not fat to be destroyed. When testing 

 whole milk, the centrifuge is run for five minutes during 

 the first run as directed in step 6. According to Ross and 

 Mclnerney,' skimmed-milk should be centrifuged ten 

 minutes during the first run. This should also be true 

 of buttermilk. The centrifuge should be operated the 

 same periods of time in the second and third runs as in 

 testing whole milk. The reason for a longer time being re- 

 quired in centrifuging skimmed and buttermilk is that the 

 fat globules which remain in these products are small and 

 are not readily brought into the neck of the test-bottle. 

 It must be remembered that special bottles should be used 

 in testing skimmed and buttermilk, and that when they 

 are placed in the centrifuge, the funnel tubes and the 

 graduated necks should be put on the same plane. This 

 permits the fat to rise more readily in the graduated neck 

 than if the bottles were placed in some other position. 



1 Ross, H. E., and Mclnerney, T. J., The Babcock Test with 

 Special Reference to Testing Cream, Cornell Univ. Agri. Exp. 

 Sta., Bui. 337, p. 35, 1913. 



