These saline matters are essential to health, and when not present in due proportion nutrition is disturbed. If a dog be fed on food freed from all salines, but otherwise containing proper nutrients, he soon suffers from weakness, after a time amounting to paralysis, and often dies in convulsions.
About 200 grains of common salt are required daily by an adult, but a large proportion of this is in our food. Phosphate of lime is obtained from milk and meats, and carbonate of lime from the hard water we drink. Both are required for the bones and teeth. The salts of potash, which assist in purifying the blood, are obtained from vegetables and fruits. An iron salt is found in most foods, and sulphur in the yolk of eggs.
106. Water. Water is of use chiefly as a solvent, and while not strictly a food, is necessary to life. It enters into the construction of every tissue and is constantly being removed from the body by every channel of waste[[17]].
As a solvent water aids digestion, and as it forms about 80 per cent of the blood, it serves as a carrier of nutrient material to all the tissues of the body.
Important Articles of Diet.
107. Milk. The value of milk as a food cannot be overestimated. It affords nourishment in a very simple, convenient, and perfect form. It is the sole food provided for the young of all animals which nourish their young. It is an ideal food containing, in excellent proportions, all the four elements necessary for growth and health in earlier youth.
| Careful analyses have beenmade of the different articles of food, mostly of the raw, or uncookedfoods. As might be expected, the analyses on record differ more or less inthe percentages assigned to the various constituents, but the followingtable will give a fair idea of the fundamental nutritive value of the morecommon foods: | ||||||
| In 100 parts | Water | Proteid | Fat | Carbohydrate | Ash | |
|---|---|---|---|---|---|---|
| Digestible | Cellulose | |||||
| Meat | 76.7 | 20.8 | 1.5 | 0.3 | — | 1.3 |
| Eggs | 73.7 | 12.6 | 12.1 | — | — | 1.1 |
| Cheese | 36-60 | 25-33 | 7-30 | 3-7 | — | 3.4 |
| Cow’s Milk | 87.7 | 3.4 | 3.2 | 4.8 | — | 0.7 |
| Wheat Flour | 13.3 | 10.2 | 0.9 | 74.8 | 0.3 | 0.5 |
| Wheat Bread | 35.6 | 7.1 | 0.2 | 55.5 | 0.3 | 1.1 |
| Rye Flour | 13.7 | 11.5 | 2.1 | 69.7 | 1.6 | 1.4 |
| Rye bread | 42.3 | 6.1 | 0.4 | 49.2 | 0.5 | 1.5 |
| Rice | 13.1 | 7.0 | 0.9 | 77.4 | 0.6 | 1.0 |
| Corn | 13.1 | 9.9 | 4.6 | 68.4 | 2.5 | 1.5 |
| Macaroni | 10.1 | 9.0 | 0.3 | 79.0 | 0.3 | 0.5 |
| Peas and Beans | 12-15 | 23-26 | 1½-2 | 49-54 | 4.7 | 2-3 |
| Potatoes | 75.5 | 2.0 | 0.2 | 20.6 | 0.7 | 1.0 |
| Carrots | 87.1 | 1.0 | 0.2 | 9.3 | 1.4 | 0.9 |
| Cabbage | 90 | 2.3 | 0.5 | 4-6 | 1-2 | 1.3 |
| Fruit | 84 | 0.5 | — | 10 | 4 | 0.5 |
Cheese is the nitrogenous part of milk, which has been coagulated by the use of rennet. The curd is then carefully dried, salted, and pressed. Cheese is sometimes difficult of digestion, as on account of its solid form it is not easily acted upon by the digestive fluids.
108. Meats. The flesh of animals is one of our main sources of food. Containing a large amount of proteid, it is admirably adapted for building up and repairing the tissues of the body. The proportion of water is also high, varying from 50 to 75 per cent. The most common meats used in this country are beef, mutton, veal, pork, poultry, and game.
Beef contains less fat and is more nutritious than either mutton or pork. Mutton has a fine flavor and is easily digested. Veal and lamb, though more tender, are less easily digested. Pork contains much fat, and its fiber is hard, so that it is the most difficult to digest of all the meats. Poultry and game have usually a small proportion of fat, but are rich in phosphates and are valued for their flavor.