5.  Smoke loaded with carbonic acid and watery vapor.

6.  Incombustible ashes.

7.  Motive force of simple alternate push and pull in the piston, which, acting through wheels, bands, and levers, does work of endless variety.

8.  A deficiency of fuel, water, or air, disturbs, then stops the motion.

The Animal Body in Life takes: 

1.  Food:  vegetables and flesh, both combustible.

2.  Water for circulation.

3.  Air for respiration.

And Produces: 

4.  A steady animal heat, by slow combustion, of 98 deg..

5.  Expired breath loaded with carbonic acid and watery vapor.

6.  Incombustible animal refuse.

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 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,           |      |     |
weighs                                                |  103 |   2 | 335
|      |     |
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 is             |   18 |  11 | 150
|      |     |
3.  Hydrogen, a gas, is a part of all bone, blood, and    |      |     |
muscle, and weighs                                    |    4 |  14 |   0