82 



CRBAMERV BUTTISR MAKING 



In the tests used for milk and cream the alkah used 

 is sodium hydroxide. This is made up of a. definite 

 strength so that the amount of acid can be calculated 

 from the amount of alkali used. 



Kinds of Tests. There are two tests in general use 

 at the present time : one devised by Prof. Manns and 



known as the Manns' Test ; 



the other devised by Prof. 



Farrington and known as Far- 



rington's Alkaline Tablet Test. 



MANNS' TEST. 



The apparatus used in this 

 test is illustrated in Fig. 28. 

 It consists of a 50 c.c. burrette, 

 a 50 c.c. pipette, a small fun- 

 nel, and a glass beaker with 

 stirring rod. The alkali (not 

 shown in the figure) can be 

 bought ready made in gallon 

 bottles and is labeled "neutral- 

 izer." This alkali or neutral- 

 izer is made by dissolving 

 four grams of sodium hydroxide in enough water to make 

 one liter solution. The solution thus formed is called a 

 one-tenth normal solution, each cubic centimeter of which 

 contains .004 of a gram of sodium hydroxide which will 

 neutralize .009 of a gram of lactic acid. 



Making the Test. Measure 50 c.c. of cream with the 

 pipette into the beaker, then with the same pipette add 

 50 c.c. of water. Now add five or six drops of indicator. 

 Ncjvt fill the burrette to the zero mark with the neutralizer 



Fig. 28.— Manns' acid test appa^ 

 ratus. 



