LABORATORY EXERCISES 



345 



74. The Babcock Test for Butter-Fat in Milk. 1 



By R. A. PEARSON, formerly Professor of Dairy Industry, Cornell University 



Materials. A hand-power centrifugal tester, at least two milk 

 test-bottles (Fig. 173), one pipette to measure the milk (Fig. 174), 

 one acid measure (Fig. 175), about one pint of sulfuric 

 acid with specific gravity between 1.82 and 1.83, a few 

 ounces of milk, and some hot water. All the 

 necessary apparatus and acid can be purchased 

 for about $5 from any dairy supply company. 

 They can be ordered through a hardware dealer. 

 Sulfuric acid is sold also at drug stores. 



Sampling the Milk. The milk to be tested 

 should be thoroughly mixed just before the 

 sample is taken, to make sure that the fat or 

 cream is evenly distributed. This can be best 

 done by gently pouring back and forth between., 

 two vessels several times. The milk should be 

 neither very cold nor hot. 



Place the small end of the pipette at the 

 center of the milk and suck the milk up above 

 the 17.6 cc. mark. Quickly put the index finger over the 

 upper end of the pipette, and by releasing the pressure allow 

 the milk to run out until its upper surface is even with 17.6 

 cc. mark when the pipette is held straight up and down. 



Place the point of the pipette a short distance into the 

 test-bottle neck, holding it against the glass, and with both 

 pipette and bottle at an angle (Fig. 176). Remove the finger 

 to allow the milk to flow into the bottle. Be sure to get 

 every drop of the milk, taking care to drain the 

 pipette and to blow the last drop into the bottle. 

 A little practice should make any one proficient 

 with the pipette. 



It is best always to make this test in duplicate; 

 hence, two bottles are needed for each lot of milk. 

 Using the Acid. The acid is very strong and 

 must be handled with great care. If any gets on 

 the hands, face or clothing, it should be washed off 

 quickly, and water should always be ready for this purpose. 

 Do not leave the acid where young children can get it. 

 'Cornell Rural School Leaflet 



Fio. 174 

 Pipette 

 or milk 



