A DAIRY LABORATORY GUIDE 7 



temperature. This is especially necessary if the 

 testing is being done in a cold room. 



The machine should always be kept well oiled 

 and securely fastened to the support on which it is 

 being operated. Skimmed milk contains such a 

 small amount of fat that the fat column could not be 

 read in an ordinary whole milk bottle. A bottle is, 

 therefore, used which has a neck with a small bore. 

 This neck is so small that the milk and acid could 

 not be poured through it, so a funnel tube is pro- 

 vided for this purpose. The skimmed milk bottle 

 should be placed in the machine in such a position 

 that the funnel tube will be on the outside. This 

 will prevent fat lodging in the space between the 

 tube and the wall of the bottle. 



The sulphuric acid is added to the milk to 

 destroy all of the milk solids except the fat, and the 

 chief solid to be destroyed is the casein. Skimmed 

 milk contains proportionately more casein than 

 does whole milk and, therefore, in making a Bab- 

 cock test of skimmed milk 2 cc. extra of sulphuric 

 acid should be used. The fat globules in skimmed 

 milk are small in size and correspondingly hard to 

 remove. A Babcock sample of skimmed milk 

 should, therefore, be whirled ten minutes, two 

 minutes and one minute. 



Cream is so viscous that it cannot be measured 

 accurately into a test bottle by means of a pipette 

 It should always be weighed. The New York state 

 dairy laws now consider it a misdemeanor to meas- 

 ure cream for testing where the tests are used as a 

 basis of payment for butter fat. 



Because the cream is sometimes too rich in butter 

 fat to be tested in an ordinary cream bottle, 9 

 grams are tested in place of 18 grams and the result 

 multiplied by two. Nine-gram cream bottles are 



