BONE contains cartilage, gelatine, fat, and the salts of lime, magnesia, soda, &c., in combination with phosphoric and other acids.

CARTILAGE consists of chondrine, a substance somewhat like gelatine, and contains also the salts of sulphur, lime, soda, potash, phosphorus, magnesia, and iron.

BILE is made up of water, fat, resin, sugar, cholesterine, some fatty acids, and the salts of potash, iron, and soda.

THE BRAIN is made up of water, albumen, fat, phosphoric acid, osmazone, and salts.

THE LIVER unites water, fat, and albumen, with phosphoric and other acids, and lime, iron, soda, and potash.

THE LUNGS are formed of two substances: one like gelatine; another of the nature of caseine and albumen, fibrine, cholesterine, iron, water, soda, and various fatty and organic acids.

How these varied elements are held together, even science with all its deep searchings has never told. No man, by whatsoever combination of elements, has ever made a living plant, much less a living animal. No better comparison has ever been given than that of Youmans, who makes a table of the analogies between the human body and the steam-engine, which I give as it stands.

ANALOGIES OF THE STEAM-ENGINE AND THE LIVING BODY.
The Steam Engine in Action takes:The Animal Body in Life takes:
1. Fuel: coal and wood, both combustible.1. Food: vegetables and flesh, both combustible.
2. Water for evaporation.2. Water for circulation.
3. Air for combustion.3. Air for respiration.
And Produces:And Produces:
4. A steady boiling heat of 212° by quick combustion.4. A steady animal heat, by slow combustion, of 98°.
5. Smoke loaded with carbonic acid and watery vapor.5. Expired breath loaded with carbonic acid and watery vapor.
6. Incombustible ashes.6. Incombustible animal refuse.
7. Motive force of simple alternate push and pull in the piston, which, acting through wheels, bands, and levers, does work of endless variety.7. Motive force of simple alternate contraction and relaxation in the muscles, which, acting through joints, tendons, and levers, does work of endless variety.
8. A deficiency of fuel, water, or air, disturbs, then stops the motion.8. A deficiency of food, drink, or air, first disturbs, then stops the motion and the life.

Carrying out this analogy, you will at once see why a person working hard with either body or mind requires more food than the one who does but little. The food taken into the human body can never be a simple element. We do not feed on plain, undiluted oxygen or nitrogen; and, while the composition of the human body includes really sixteen elements in all, oxygen is the only one used in its natural state. I give first the elements as they exist in a body weighing about one hundred and fifty-four pounds, this being the average weight of a full-grown man; and add a table, compiled from different sources, of the composition of the body as made up from these elements. Dry as such details may seem, they are the only key to a full understanding of the body, and the laws of the body, so far as the food-supply is concerned; though you will quickly find that the day's food means the day's thought and work, well or ill, and that in your hands is put a power mightier than you know,—the power to build up body, and through body the soul, into a strong and beautiful manhood and womanhood.

ELEMENTS OF THE HUMAN BODY.
Lbs.Oz.Grs.
1.Oxygen, a gas, and supporter of combustion, weighs1032335
2.Carbon, a solid; found most nearly pure in charcoal. Carbon in the body combines with other elements to produce carbonic-acid gas, and by its burning sets heat free. Its weight is1811150
3.Hydrogen, a gas, is a part of all bone, blood, and muscle, and weighs4140
4.Nitrogen, a gas, is also part of all muscle, blood, and bone; weighing4140
5.Phosphorus, a solid, found in brain and bones, weighs11225
6.Sulphur, a solid, found in all parts of the body, weighs080
7.Chlorine, a gas, found in all parts of the body, weighs04150
8.Fluorine, supposed to be a gas, is found with calcium in teeth and bones, and weighs03300
9.Silicon, a solid, found united with oxygen in the hair, skin, bile, bones, blood, and saliva, weighs0014
10.Magnesium, a metal found in union with phosphoric acid in the bones02250
11.Potassium, a metal, the basis of potash, is found as phosphate and chloride; weighs03340
12.Sodium, a metal, basis of soda; weighs03217
13.Calcium, a metal, basis of lime, found chiefly in bones and teeth; weighs313190
14.Iron, a metal essential in the coloring of the blood, and found everywhere in the body; weighs0065
15.Manganese.}
16.Copper metals.} Faint traces of both these metals are found in brain and blood, but in too minute portions to be given by weight.
Total15400