DAIRY HUSBANDRY 
15 
EXERCISE NO. 9 
Object: To make an accurate test of partially churned milk. 
Procedure: A fat test of partially churned milk is one of the most difficult 
tasks of testing, for exceptional care must be taken to obtain 
reliable results. 
A. Obtain about 500 cc. (1 pint) of milk, having a temperature be¬ 
low 60° F. Measure out duplicate samples. Divide the re¬ 
maining milk into three approximately equal parts. Redivide 
one of the tree lots in two equal parts and set aside in the 
locker for future use. Then proceed as follows: 
(1) Cap one of the two remaining containers securely and shake 
with a churning motion until large butter granules form. 
Do not mistake foam for butter. 
(a) Melt the fat in the churned sample by placing the con¬ 
tainer in warm water (110° F.) until all of the granules 
have liquified. 
(b) Shake the mixture vigorously until completely mixed. 
(c) Sample at once for testing. 
Note: This step requires very great care and rapidity 
of operation, since liquid fat in the form of large fat glob¬ 
ules separates very rapidly from the serum. 
(2) Cap the second container securely and churn the sample as 
above. 
(a) Add a known quantity of ethyl ether (10-20 cc. will 
usually suffice) to dissolve the butter granules. 
(b) After the granules have been completely dissolved, mix 
thoroughly and test in duplicate. Calculate the per 
cent fat according to F. & W. If 31. 
Note: Care should be exercised in adding acid to warm 
milk or to milk containing ether. A few cc.’s should 
be added at a time and the bottle well shaken after each 
addition, as otherwise the action may be very violent. 
