CAEE OF MILK ON THE FAEM 



347 



percentage of fat. The skiin-niilk test is valuable for testing the 

 completeness of the skinnning, but its results must not be 

 interpreted too strictly. 



The skim-milk test bottle differs from the whole-milk test 

 bottle in having two necks, one of small bore graduated to read 

 hundredths per cent for the fat column, and one extending nearly 

 to the bottom of the bottle for filling. 



Seventeen and one-half cubic centimeters of the skim milk are 

 placed in the test bottle through the filling tube. Twenty cubic 

 centimeters of sulphuric acid are added in two portions of ten 

 cubic centimeters each, shaking after each addition. Great care 

 nmst be taken, while shaking, to be sure that no particles reach 

 the fat tube; otherwise it will become plugged and the test 

 ruined. The test bottles are placed in the tester with the filling 

 tubes toward the center. The first whirling is continued one or 

 two minutes longer than when testing whole milk. As in whole- 

 milk testing, hot water is added in two portions, the second one 

 bringing the fat about half-w^ay up the tube. The reading should 

 be made immediatelv after the final whirling. If the fat is in 



Fig. 176. — Modern barns and buildings on Davey Experimental Farm of the Federal 

 Bureau of Animal Industry at Beltsville, Md. 



