DAIRY HUSBANDRY 
19 
EXERCISE NO. II 
Object: To determine the rapidity with which fat rises on milk. 
Procedure: Since butterfat maintains its identity in the milk and is in 
suspension, it rises to the surface due to the fact that its spe¬ 
cific gravity is considerably less than that of the serum. The 
rapidity with which the fat rises, however, depends on other 
factors beside specific gravity. 
A. Fill three cylinders with a well mixed sample of milk previously 
tested in duplicate. 
B. Test the top layer and the bottom layer of milk in cylinder 
number 1 after it has stood 10 minutes. First remove samples 
from the top—then by closing the upper end of the pipette, 
lower it in the milk and remove a sample from the bottom of 
the cylinder. 
C. Repeat the above process with the second cylinder after 20 
minutes. 
D. Repeat the above process with the third cylinder after 30 
minutes. 
Observations: 
San 
iple 
Time Stood 
Layer 
Results 
Color 
Condition 
1 
a 
b 
2 
a 
b 
• 
3 
a 
b 
4 
a 
b 
Conclusions: 
Questions: (1) Name the fats of which butter fat is composed, and state 
how the various butter fats differ from each other. 
(2) How can true butter be distinguished from oleomargarine? 
(3) Name the factors which influence the rapidity with which fat 
rises on milk. 
(4) Describe butter fat globules with reference to size, number, 
shape etc• 
References: F. ’& W. IF 15, 17, 29; Van S. pp. 3-8; jud. pp. 25-26; St., 
pp. 20-23, 69-73. 
