32 PROFITABLE DAIRYING 



fat into a clear layer of oil. Sometimes several 

 churnings and consequent reclmrnings were nec- 

 essary to make a clear test. This test, known 

 as the churn test, was a slow, laborious, and 

 somewhat unreliable process. 



Fig. 4. The two principal types of hand testers. 



The test measures the fat. In the Babcock 



test the separation of butter fat from the other 

 constituents is accomplished in a few minutes. 

 The curd is dissolved by a strong acid which 

 will not act upon the fat. The fat globules are 

 brought to the surface by whirling in a machine 

 called a centrifuge. This layer of fat is brought 

 up into the neck of the test bottles into which 

 the samples of milk were placed at the begin- 

 ning of the test, and the percentage of fat read 

 directly from the neck of the test bottle. The 

 entire test takes about ten or fifteen minutes of 

 time, is thoroughly reliable, and can be made by 

 anyone possessing ordinary intelligence. 



