MIXING MORNING’S AND NIGHT’S MILK 125 
may smell or taste and is more difficult to re- 
move from milk than stove heat. The fact is 
that animal heat is just heat. Animal heat is 
removed from milk by cooling of any kind. Ani- 
mal heat will all escape from milk through the 
sides of a can or bottle when standing in cold 
water. 
MIXING MORNING’S AND NIGHT’S MILK 
There is supposed to be some mysterious chem- 
ical action that takes place between morning’s 
milk and night’s milk when they are mixed, which 
results in the rapid souring of the mixture. The 
mixture is supposed to sour much more rapidly 
than either the night’s milk or the morning’s 
milk would if left alone, consequently, dairymen 
keep morning’s milk and night’s milk separate. 
The truth is that souring of milk is the result 
of the growth of bacteria which produce lactic 
acid out of the milk sugar. If night’s milk has 
been kept cold it stays sweet, because the bac- 
teria do not grow in the cold. Warm morning’s 
milk is sweet because it is fresh. Morning’s 
milk will sour in a few hours if not cooled. If 
morning’s milk is mixed with night’s milk it 
