ACIDITY TESTS. 41 



47. Farrington standard acidity test apparatus. 



1 Babcock 17.6 c. c. pipette ; 1 white cup ; 2, 100 c. c. 

 graduated cylinders ; 1 box of 1,000 tablets. 



48. Farrington rapid method acidity test. This 

 method for determining acidity in milk or cream is 

 used mainly where quick results are desired and 

 when a great number of tests must be made in a 

 short time. For selecting milk for pasteurizing or 

 for testing milk quickly for city supply this test is 

 indispensable because it is convenient and accurate 

 and the solution is very easily prepared. 



49. How the solution is prepared. Take one al- 

 kaline tablet and dissolve it in one ounce of soft 

 water and when dissolved use as needed. Do not 

 prepare more of the solution than is needed for a 

 day or two. When all is not used soon after pro- 

 paring pour it into a bottle and cork well or else 

 throw it away and prepare a fresh solution when 

 needed. 



50. How to use the test. This test is based upon 

 the use of equal quantities of cream or milk and 

 solution. A measure of the same size as that used 

 for measuring the cream or milk must be used for 

 measuring the solution. One measure of the solu- 

 tion added to an equal measure of milk or cream 

 represents .10 per cent acidity and two measures 

 represents .20 per cent, and so on. Half per cents 

 can be obtained by a half measure of the solution. 

 Stop adding solution when a light pink shade ap- 

 pears. This applies to all the acidity tests men- 

 tioned. 



