120 



Testing Milk and Its Products. 



142. Sgillman's cylinder. The graduated cylinder shown 

 in Fig. 42 was devised by Professor Spillman for use in 

 testing the acidity of milk and cream with 

 Farrington's alkaline tablets. The follow- 

 ing directions are given for making tests 

 with this piece of apparatus: 1 



"All that is needed in addition to the acid test 

 graduate shown in the accompanying illustra- 

 tion, is a common prescription bottle of six or 

 eight ounce capacity, and a package of Farring- 

 ton's alkaline tablets. Fill the bottle with water 

 and add one tablet for each ounce of water in 

 the bottle. Shake the bottle frequently to aid 

 in dissolving the tablets. 



"Making the test. In making the test, the 

 .. acid-test graduate is filled to the zero mark with 

 I ,FIG. 42. spill- the milk or cream to be tested. The tablet solu- 



u^ed' 8 in^dSer- tion is the11 added > a Uttle at a tim6 ' and the 

 Dining the acid- graduate shaken after each addition, in order to 



ity of cream or thoroughly mix the milk and the tablet solution. 

 milk - In shaking the graduate, give it a rotary motion 



to prevent spilling any of the liquid. Continue adding the 

 tablet solution until a permanent pink color can be detected in 

 the milk. The level of the liquid in the graduate, measured by 

 the scale on the graduate, will then be the per cent, of the acid- 

 ity of the milk. It is best to stand the graduate on a piece of 

 white paper, so that the first pink coloration of the milk may 

 be easily detected." 



143. Rapid estimation of the acidity of apparently sweet 

 milk or cream, a, Milk. The alkaline tablet method offers 

 a ready means of estimating the acidity of milk or cream 

 that is still apparently sweet. The selection of the best 

 kinds of milk is especially important in pasteurizing milk 

 or cream. Investigations have shown that milk which 

 gives the highest acid test contains, as a rule, a larger 



i Washington experiment station, bulletin No. 24. 



