constituents; but to cook intelligently, with that success which makes
for actual economy and digestibility, certain facts must be known
concerning the food principles and the effect of dry and moist heat
on foods.

12. Water.--Of the various constituents that are found in the human
body, water occurs in the largest quantity. As a food substance, it is
an extremely important feature of a person's diet. Its chief purpose is
to replenish the liquids of the body and to assist in the digestion of
food. Although nature provides considerable amounts of water in most
foods, large quantities must be taken in the diet as a beverage. In
fact, it is the need of the body for water that has led to the
development of numerous beverages. Besides being necessary in building
up the body and keeping it in a healthy condition, water has a special
function to perform in cooking, as is explained later. Although this
food substance is extremely essential to life, it is seldom considered
in the selection of food, because, as has just been mentioned, nearly
all foods contain water.

13. Mineral Matter.--Ranking next to water in the quantity contained in
the human body is mineral matter. This constituent, which is also called
_ash_ or _mineral salts_, forms the main part of the body's framework,
or skeleton. In the building and maintaining of the body, mineral salts
serve three purposes--to give rigidity and permanence to the skeleton,
to form an essential element of active tissue, and to provide the
required alkalinity or acidity for the digestive juices and other
secretions.

The origin and distribution of these mineral substances are of interest.
Plants in their growth seize from the earth the salts of minerals and