The result is that the ice tends to become liquid and the contents of
the can solid by the exchange of temperatures. To make the mixture of
uniform consistency, it is usually agitated by means of a dasher during
the freezing process. This incorporates air into the mixture and
consequently makes it light and increases its volume.

60. PROPORTION OF ICE TO SALT.--The ingredients used in the mixture have
much to do with the texture of the ice cream when it is frozen. For
instance, a mixture that is thin and composed largely of water will not
have so smooth a consistency when frozen as a heavier mixture in which
cream or eggs or both are present and a smaller proportion of water is
used. Another important factor in the texture of the finished product is
the proportion of ice to salt, for this has much to do with the length
of time required for freezing the mixture. The smaller the proportion of
salt, the slower will be the freezing process, for the melting of the
ice takes place more slowly; but the result of this slow freezing is a
finer, smoother texture. Granular, coarse-grained frozen desserts, such
as some sherbets and frappes, are frozen with a large proportion of
salt, which permits the freezing to take place more quickly.

61. On this rapidity in freezing also depends to a large extent the
increase in quantity that takes place in the frozen mixture. Any one who
has had experience in making ice cream knows that the can of the freezer
cannot be filled before the freezing is begun or it will overflow during
the freezing process. Even if it is only two-thirds or three-fourths
full, it will be entirely full when the freezing is completed. This
increase depends somewhat on the kind of mixture, as has been stated, as
well as on the way in which the crank of the freezer is turned, but it
is more largely determined by the proportion of ice and salt and
consequently by the length of time required for the freezing. As can be