Testing the Acidity of Milk and Cream. 129 



(45. Spillman's cylinder. The graduated cylinder shown in 

 fig. 43 was devised by Professor Spillman for use in testing the 

 acidity of milk and cream with Farrington's alkaline tablets. 

 The following 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 illustration, 

 is a common prescription bottle of six or eight 

 ounce capacity, and a package of Farrington'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 dis- 

 solving, the tablets. 



"Making the test. In making the test, the 

 acid-test graduate is filled to the zero mark with 

 the milk or cream to be tested. The tablet solu- 

 tion is then added, a little at a time, and the 

 graduate shaken after each addition, in order to 

 t thoroughly mix the milk and the tablet solution. 



In snaking the graduate, give it a rotary motion 

 FIG. 43. Spill- . .,,. .. ,. . , Vi 



man's cylinder, to prevent spilling any of the liquid. Continue 



mfifln^theaclci- addin g tne tablet solution until a permanent pink 

 ity of cream or color can be detected in the milk. The level of 

 the liquid in the graduate, measured by the scale 

 on the graduate, will then show the per cent, of the acidity 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 de- 

 tected. ' ' 



146. The Marschall acid test (see fig. 44) is a con- 

 venient apparatus for determining the acidity of milk, 

 cream, or whey. 2 It is used with tenth-normal alkaline 

 solution ("Nentralizer"), 9 cc. of milk, cream, etc., 

 being measured out for the test, and alkali solution 

 added from the combined burette and bottle, the former 

 being graduated to two-tenths of one cc. With the 



1 Washington experiment station, bulletin 24. 



2 See Wis. exp. sta. bull. 129. 



9 



