DAIRY HUSBANDRY 
17 
EXERCISE NO. 10 
Object: To test thick soured milk for fat. 
Procedure: “When milk becomes sour, the casein is coagulated and the 
mechanical condition of the milk thereby changed so as to 
render difficult a correct sampling.” (F. & W. f 32.) 
A. The two samples of milk held over from Exercise 9 to sour and 
thicken, are liquified by the following two methods: 
(1) To one of the samples add a small quantity O^-T gram) of 
some solid alkali (sodium hydroxide or potassium hydrox¬ 
ide). Shake from time to time, and when completely 
liquified obtain duplicate samples for testing. 
Note: Do not try to hasten the process by a too rapid ad¬ 
dition of the alkali. 
(2) To the second sample add a definite quantity (2-5 cc. may 
be sufficient) of strong aqua ammonia in quantities of 1 cc., 
and shake well after each addition. When the sample has 
been completely liquified, obtain duplicate samples for 
testing. Calculate the correct test as for partially churned 
milk. 
Note: (1) Extreme care should be exercised when adding 
acid to an alkaline solution. Avoid accidents by adding 
the acid in small quantities. 
(2) A soda washing powder, e. g., Wyandotte may be sub¬ 
stituted for either of the above alkalies. 
Observations: 
Sample 
cc. of 
milk 
Alkali 
used 
Amount 
of alkali 
Reading 
% fat 
1 
a 
b 
2 
a 
, 
b 
3 
a 
b 
i 
Conclusion: 
