48 DAIRY CHEMISTRY 



is first added and the milk is stirred, the color is not 

 permanent, but after a sufficient amount of alkali is 

 added, a point is reached when two or three drops 

 more will produce a permanent color. In making 

 comparative tests, the operator should always aim to 

 secure the same degree of color in all the samples 

 tested. Strong alkali water is not suitable for wash- 

 ing the milk dishes or for diluting the milk in mak- 

 ing this test. 



54. Alkaline Tablets. Because of the difficulty in 

 preparing and securing the tenth normal solution, 

 Farrington and others have proposed the use of 

 alkaline tablets. These tablets are so prepared as to 

 contain a definite quantity of alkali mixed with the 

 requisite indicator or coloring matter. When used, 

 the tablets are to be dissolved in pure rain or distilled 

 water. To prepare the ordinary tablet solution 

 five are placed in a 100 cc. glass-stoppered cylinder 

 filled with 97 cc. of water, and when dissolved this 

 gives an alkali solution of the requisite strength. 

 In making the test, 17.6 cc. of milk or cream is 

 measured into a porcelain cup, and the alkali solution 

 added from the cylinder until the pink color becomes 

 permanent. The amount of the tablet solution used 

 is found by reading the amount of solution remain- 

 ing in the cylinder and subtracting it from the origi- 

 nal quantity. The number of cubic centimeters of 

 tablet solution used, divided by 100, gives directly 

 the percentage of acid in the sample. If 17.6 cc. of 

 cream requires 40 cc. of tablet solution to produce 



