The remaining ingredient of the food of our breakfast to be considered is the mineral matter which constitutes the ash when food-products are burned. There is only 5 or 6 per cent of mineral elements in our bodies, but these materials are necessary to life and health. They are found chiefly in the bones and teeth, but are present also in the flesh, blood, and other fluids. Phosphate of calcium forms the principal mineral part of the bones.

The food we eat contains a small amount of mineral matter which forms the ashes when food is burned.

Effect on Solubility

Common Salt

This mineral matter gives the body the mineral salts which it needs; but in addition to this, most people desire and eat a considerable quantity of common salt every day. The amount eaten is far in excess of the sodium and chlorine the body requires, though sodium is an important constituent of many of the fluids of the body, and chlorine is found in hydrochloric acid of the gastric juice, the digestive fluid of the stomach. A great diversity of opinion exists as to the desirability of much salt in the diet, but the balance of evidence indicates that a liberal amount of salt is not harmful, but rather beneficial.

Experiment. To show the mineral part of bones, place a moderate sized bone on a hot coal fire for half an hour or longer.

To show the gelatinoids of bones, place a small bone in a shallow dish and cover with strong vinegar or weak hydrochloric acid (muriatic acid) and let stand over night or longer. The acid will dissolve out the phosphate of calcium leaving the animal matter.

Coffee, an important part of the breakfast to most people, introduces an important feature of the chemistry of cooking - the production of the proper flavor. The chemical changes involved are too subtile for explanation here - indeed many are not understood. The change in the coffee berry by roasting is a familiar illustration. The heat of the fire causes the breaking up of a substance existing in the berry, and the formation of several new ones. If the heat is not sufficient, the right odor will not be given; if it is too great, the aroma will be dissipated into the air, or the compound will be destroyed.

Broiling steak is another illustration - a few seconds too long, a few degrees too hot, and the delicate morsel becomes an irritating mass. The chemistry of flavor-producing is the application of heat to the food material in such a way as to bring about the right changes and only these. Flavors in addition to the pleasure they give to eating have the advantage of stimulating the flow of digestive fluids and making digestion more easy.