It is a fact that cream rises best in a falling temperature, very
slowly in a stationary one, and little or none in a rising temperature.
Hence, in cold weather, when milk cools very rapidly after being drawn
from the cow, it is the practice of many good dairymen to raise the
temperature of the milk to 100 degrees when set. In this way, they get
a quicker and more complete separation of the cream as the milk cools
down.
It would be a good idea to have, in all butter factories, apparatus
for setting milk so constructed that the temperature of the mass
of milk can be gradually and evenly raised to 100 degrees, or even
slightly above; for it is difficult to deliver warm milk in a good
condition especially in hot weather--if it has to be carried any
considerable distance, while in cold weather, it is sure to get
considerably reduced in temperature, both in milking and on the road to
the factory. Hence, it seems almost absolutely essential, if the best
results are to be attained, to have some means of properly raising the
temperature of the milk at the factory.