50 CHEESE MAKING. 
FIRST STEPS IN CHEESE MAKING, 
106. Test for Over-Ripe Milk. 
Milk that has more than two-tenths of 1 per cent of lactic 
acid should not be received for cheese making. As milk 
will not taste sour until it reaches nearly three-tenths of 1 per 
cent of acid, it is difficult to determine by the taste when to re- 
ject such milk. 
The Farrington acid test can here be brought into use and 
the discrimination quickly made. The apparatus consists of a 
¥ 
HNL lai 
& Ounce Bottle. Measure 
Ce 
Fig. 23.—Farington’s apparatus for rapid estimation of the acidity of 
apparently sweet milk or cream. 
white teacup, an eight-ounce wide-mouth bottle, and a measure 
made by soldering a wire handle onto a No. 10 brass cartridge 
shell. Eight Farrington alkaline tablets are dissolved in the 
eight-ounce bottle of water, which makes a red liquid. <A 
measure of the suspected milk is put into the teacup and then 
two measures of the red liquid added. If on stirring it, the pink 
shade remains, there is not two-tenths of a per cent of acid 
present and the milk can be accepted. If, on the other hand, the 
pink color disappears, there is too much acid present and the 
milk should be rejected.* 
* See “Testing Milk and Its Products,” 22d ed., p. 188. 
