These simple substances are constantly passing out of the body through the lungs, skin, and other excreting organs. It is found that certain of these simple elements are used for one part of the body and others for other parts, and this in certain regular proportions. Thus, carbon is the chief element of fat, and also supplies the fuel that combines with oxygen in the capillaries to produce animal heat. The nitrogen which we gain from our food and the air is the chief element of muscle; phosphorus is the chief element of brain and nerves; and calcium or lime is the hard portion of the bones. Iron is an important element of blood; and silicon supplies the hardest parts of the teeth, nails, and hair. Water, which is composed of the two gases oxygen and hydrogen, is the largest portion of the body, forming its fluids; there is four times as much of carbon as there is of nitrogen in the body; while there is only two per cent. as much phosphorus as carbon. A man weighing one hundred and fifty-four pounds, who leads an active life, takes into his stomach daily from two to three pounds of solid food, and from five to six pounds of liquid. At the same time he takes into his lungs, daily, four or five thousand gallons of air. This amounts to three thousand pounds of nutriment received through stomach and lungs, and then expelled from the body, in one year; or about twenty times the man’s own weight. It is found that the simple elements will not nourish the body in their natural state, but only when organized, either as vegetable or animal food; and, to the dismay of the Grahamite or vegetarian school, it is now established by chemists that animal and vegetable food contain the same elements, and in nearly the same proportions. Thus, in animal food, carbon predominates in fats, while in vegetable food it shows itself in sugar, starch, and vegetable oils. Nitrogen is found in animal food in the albumen, fibrine, and caseine; while in vegetables it is in gluten, albumen, and caseine.