208 



BUTTER-MAKING. 



divided by the 50, and multiplied by 100, would give the per- 

 centage of the acid present. 



Farrington Test. The same principle is involved in the 

 P'arrington test. The alkali is put up in small tablets, already 

 containing the indicator. These tablets contain a definite 

 amount of alkali, and are represented as retaining their strength. 

 However, they lose their strength if they are exposed to the 

 atmosphere. The amount of alkali embodied in each tablet is 

 such that when five of them are taken into a graduated cylin- 

 der, the cylinder filled up with distilled water to the 97-c.c. 



FIG. 132. Apparatus for the Farrington acid test. 



mark, and the tablets thoroughly dissolved in water, a solution 

 is obtained, each cubic centimeter of which represents .01 of 

 1% of acid, providing 17.6 c.c. of cream is taken. The tablets 

 can be made up of different strengths for the use of different- 

 sized pipettes, but as the 17.6-c.c. pipette is the one which is 

 used in the ordinary Babcock test, directions are given for the 

 use of that pipette only. For a more detailed description of 

 the acid tests see "Milk Testing," by Farrington and Woll. 



Amount of Acid to Develop. The amount of acid to develop 

 in cream depends upon the amount of fat present in the cream, 

 and to some extent upon the market on which the butter is 



