84 MARKET DAIRYING 
In the tests used for milk and cream the alkali 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. 32. 
It consists of a 50 c.c. burette, 
a 50 ¢.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- 
Fag 2s —Minuns acl sesh eepe yee” “This alkali of niemtral= 
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 .oog 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. 
Next fill the burette to the zero mark with the neutralizer 
