428 SCIENCE AND i'RACTICE OF CHEESE-MAKING 



ing a tenth-normal alkali solution, a concentrated solu- 

 tion of caustic soda is advised, of which 50 cc. is suffi- 

 cient to make 2,300 cc. of a tenth-normal solution. This 

 solution retains its strength indefinitely when tightly 

 corked. The tenth-normal solution is prepared by 

 adding the contents of the small bottle of alkali to the 

 large bottle without any loss, rinsing the small bottle 

 several times and each time pouring the rinsings into 

 the large bottle. Soft water is then added to the large 

 bottle until it reaches the level of the mark (2,300 cc.) 

 filed on the bottle. In order to keep this alkali solution 

 without loss of strength, the small wash-bottle referred 

 to above (2) is attached to the neck of the larger one 

 in the manner indicated, after being half filled with the 

 tenth-normal alkali solution. 



(3) Method of use. — The liquid to be tested (milk, 

 whey, cream or starter) is measured by means of the 

 9-gram pipette and run into the white cup. Two drops 

 of phenolphthalein solution are added, after which the 

 alkali, a drop at a time, is run into the cup from the 

 burette (arranged in the manner indicated on p. 422), 

 until the solution in the cup, which must be constantly 

 stirred, shows a very faint pink color that does not 

 disappear for 15 seconds or longer. Each tenth cc. of 

 alkali used represents .01 per cent of acid. 



Manns' acid test. — For details see Testing Milk, 

 etc., pp. 101-103. 



Farrington's alkaline tablet test. — In this form of 

 test, the alkali and indicator are mixed together in the 

 form of tablets. Five tablets are dissolved so as to 

 make 97 cubic centimeters of solution, which is added, 

 in small portions, from a graduated cylinder to 17.5 

 cubic centimeters of milk until the pink color re- 

 mains. Each cubic centimeter of alkali solution 



