machinery especially designed for the purpose. The greater the
proportion of fat in milk, the thicker, or "heavier," will be the cream.

Various grades of separated cream are placed on the market, the usual
ones being those which contain 8, 12, 16, 20, and 40 per cent, of fat.
Thin cream, which includes the grades that have only a small percentage
of fat, contains a larger quantity of milk than the others and is not so
desirable for many purposes. Still, it is used to some extent, because
it is cheaper and there are definite uses to which it can be put.
Medium-heavy cream is the kind to select when it is desired for
_whipping_. This is a process that consists in beating the cream rapidly
until a mass of tiny bubbles form and become stiff, very much as the
white of egg does.

15. SKIM MILK.--After a part or all of the cream has been removed from
whole milk, that which remains is called skim milk. While practically
all of the fat is taken out when milk is skimmed, very little protein or
sugar is removed. Therefore, skim milk is still a valuable food, it
being used to a large extent for cheese making, for the manufacture of
certain commercial foods, and for the feeding of animals. The housewife
does not, as a rule, buy skim milk; indeed, in some localities the laws
prevent its sale because it is considered an adulterated food. However,
it is really a wholesome, valuable food that is cheaper than whole milk,
and its use in the home should therefore be encouraged from an
economical standpoint. Here it may be used in the preparation of many
dishes, such as sauces, cakes, biscuits, muffins, griddle cakes, bread,
etc., in which butter or other fats are used, and in custards, puddings,
ices, and numerous other desserts.

16. BUTTERMILK.--The milk that remains in butter making after the butter