COMPOSITION OF MILK. 13 
by melting a sample of butter which contains these different 
fats, the fats with a low melting-point would melt first, and 
leave the remainder in an unmelted condition. Such is not 
the case. Butter-fat in this respect behaves a good deal like 
different metals with different fusing-points. When they are 
melted and mixed together, cooled and then remelted again, 
they assume a common melting-point. It is the same way 
with butter-fat. It melts at a temperature of 91° to 
96° F. 
As the body temperature of cows (about 98° F.) is above 
this temperature, the fat globules are present in the milk in 
liquid form when milk is first drawn. A peculiarity about 
these fat-globules in milk is that the milk and fat may be cooled 
down below the melting-point of the fat of butter without 
the fat-globules in milk being solidified. It requires'a tem- 
perature of between 60° and 78°F. before the fat-globules 
in milk begin to solidify. When these small fat-globules are 
caused to unite, as during the churning process, they solidify 
at higher temperature. This behavior of the fat in milk evi- 
dently must be due to a relative change in the position of the 
molecules of fat during the process of cooling and warming. 
No definite explanations, so far as is known, have been given 
for this condition of the fat. 
The non-volatile fats found in butter-fat are practically 
the same as those found in other animal fats. 
Composition of Butter-fat—aIn his ‘“ Dairy Chemistry,” 
Richmond gives the following composition of butter-fat, repre- 
senting the mean results obtained by different observers: 
; r Butyrin. ........ 3.85% 
8% Volatile......... | Caproin,, ....... 3.60% 
Caprylin,........ 55% 
Fat...... Caprin.......... 1.9% 
Laurin, ......... 7.4% 
sung Myristin, ........ 20.2% 
Bay Nem-yolnlleasie 4 itn cas noe 25.7% 
Stearin.......... 1.8% 
