76 FIRST LESSONS IN DAIRYING 



When testing individual cow's milk it is necessary 

 that the milking be completed and the entire yield 

 of milk mixed before sampling. The milk from the 

 several quarters of the udder may differ in the per 

 cent, of fat. The first milk drawn may test only 

 .8 per cent, fat, and the last 8 to 12 per cent. 



The acid. The acid used is commercial sulphuric, 

 having a specific gravity of 1.82 to 1.83. If the acid 

 is too weak, more must be used ; if too strong, less 

 may be used. Because of the power to absorb mois- 

 ture from the air, the bottle should be kept tightly 

 stoppered unless the acid is too strong and it is 

 desired to thus weaken it. When adding to the 

 sample, the test bottle should be so slanted as to 

 allow the acid to run down the side of the bottle. 

 The acid and milk should be mixed immediately, 

 since standing allows the milk next to the acid to 

 become burned. 



Whirling. After the acid and milk are mixed the 

 bottle should be whirled in the centrifuge for five 

 minutes ; stopped and water added up to the neck of 

 the bottle ; whirled one minute and filled to the 8 

 or 9 per cent, mark, and whirled one more minute. 

 The water used in hand testers should be boiling 

 hot, and should be either rain water or well water 

 that is free from lime or other foreign material. It 

 can best be added with a narrow-lipped or spouted 

 cup, or with the pipette. Care must be used not to 

 burn the mouth when using the pipette. 



Reading. This should be done with the bottles 

 at a temperature of from 120 to 140. If necessary, 

 the bottles can be placed in a bath of warm water 



