Water.

By referring to a preceding chapter we find that water composes three-fifths of the entire body.  The elasticity of muscles, cartilage, tendons, and even of bones is due in great part to the water which these tissues contain.  The amount of water required by a healthy man in twenty-four hours (children in proportion) is on the average between 50 and 60 ounces, beside about 25 ounces taken as an ingredient of solid food, thus making a total of from 75 to 85 ounces.  One of the most universal dietetic failings is neglect to take enough water into the system.  Dr. Gilman Thompson gives the following uses of water in the body:—­

(1) It enters into the chemical composition of the tissues; (2) it forms the chief ingredient of all the fluids of the body and maintains their proper degree of dilution; (3) by moistening various surfaces of the body, such as the mucous and serous membranes, it prevents friction and the uncomfortable symptoms which might result from drying; (4) it furnishes in the blood and lymph a fluid medium by which food may be taken to remote parts of the body and the waste matter removed, thus promoting rapid tissue changes; (5) it serves as a distributer of body heat; (6) it regulates the body temperature by the physical processes of absorption and evaporation.

Salts (Mineral Matter).—­Use of Salts in Food.

(1) To regulate the specific gravity of the blood and other fluids of the body; (2) to preserve the tissues from disorganization and putrefaction; (3) to enter into the composition of the teeth and bones.  These are only a few of the uses of salts in the body, but are sufficient for our purpose.  Fruits and nuts contain the least quantity of salts, meat ranks next, then vegetables and pulses, cereals contain most of all (Chambers).  Sodium chloride (common salt) is the most important and valuable salt.  It must not however be used in excess.  Potassium salts rank next in importance.[4] Calcium, phosphorus, sulphur and iron are included in this class.

The quantity of salts or mineral matter contained in some important articles of vegetable and animal food is shown in this table (Church): 

Mineral Matter in 1,000 lbs. of 14 Vegetable Products.

Lbs. 
Apples                    4
Rice                      5
Wheaten flour             7
Turnips                   8
Potatoes                 10
Barley                   11
Cabbage                  12
Bread                    12
Watercress               13
Maize                    20
Oatmeal                  21
Peas                     30
Cocoa nibs               36
Wheaten bran             60

Mineral Matter in 1,000 lbs. of 8 Animal Products.

Lbs. 
Fat Pork                  5
Cow’s milk                7
Eggs (without shells)    13
Lean of mutton           17
Flesh of common fowl     16
Bacon                    44
Gloucester cheese        49
Salted herrings         158

“In most seeds and fruits there is much phosphate in the mineral matter, and in most green vegetables much potash.  One important kind of mineral matter alone is deficient in vegetable food, and that is common salt.”