THE USE OF THE BABCOCK TESTER 17 



finely pulverized cheese, using 9 grams in each test, 

 and multiplying the result by 2. Obtain accurate 

 sample by inserting trier in various places in the 

 cheese or butter to be tested. 



Also test samples of ice cream using a mixture of 

 equal parts of Cone, hydrochloric acid and glacial 

 acetic acid. 



Hydrochloric acid alone chars the milk sugar on 

 heating almost as bad as sulphuric acid, and, there- 

 fore, is useless. Acetic acid alone will not dissolve 

 the milk solids, but the mixture works perfectly. 



When milk has become sour the casein may be 

 redissolved by adding powdered potash, baking soda, 

 or liquid ammonia. Care should be taken not to 

 use too much alkali as it reacts with the acid and 

 sometimes throws a part of the sample out of the 

 bottle. Dissolve the potash or soda in water before 

 using. A volume equal to about 5 per cent of the 

 volume of the milk will be sufficient to dissolve the 

 casein. This solution increases the volume of milk 

 and thus necessarily decreases the per cent of fat. 

 Measure the volume of milk to be tested, and meas- 

 ure the solvent before adding. Calculate the de- 

 crease in the per cent of fat in the following manner : 



If 9 cubic centimeters of alkaline solution has been 

 added to 180 cubic centimeters milk to dissolve the 

 casein, which is 5 per cent of the milk used (180 : 9 : 

 :100:x=5), the mixture gives a test of 3.9 per 

 cent of butter fat. The test must be increased 0.195 

 per cent (3.9 X .05 = 0.195). Hence, the per cent of 

 fat in the original milk is 4.095 (3.9 + 0.195 = 4.095). 



