Let us find the antipodes of weight. Iridium, hammered to increase its density, is twenty-three times heavier than water; water is about eight hundred times heavier than air, and air is fourteen times heavier than H: 23×800×14=257,600; that is, one quart of Ir would balance 257,600 quarts of H.
OXYGEN.
There are four kings among chemical substances: Oxygen, king of all the elements; gold, king of the metals; oil of vitriol, king of the acids, and potash, king of the bases.
PREPARATION OF OXYGEN FROM MERCURIC OXIDE—MATERIALS USED BY DR. PRIESTLY.
This term of distinction is given to oxygen because of its marvellous activity and range of powers; it unites with all elements save one, fluorine. Its grasping disposition is often resisted by man; he keeps it from destroying his house by painting it; from gnawing at the quivering nerves of his teeth by filling them; from devouring his fruits by canning them; and Monsieur Goffart has now taught us to save green food for our cattle, from its ravages by excluding O from our silos. In spite of its destroying power we can not live without it. The light and warmth in our homes are produced by its rapid union with fuel. Every moment we breathe we are absorbing it into our bodies, where it unites with waste matter, producing heat and energy, and removing that which would clog and poison the system. There is nothing in nature more beautiful than the plan by which the animal and vegetable kingdoms mutually sustain each other by the interchange of O. Look at this little aquarium; here are two or three shiners, some goldfish, and a few water plants. In this little world we may see exactly what goes on in the great world. That goldfish is inhaling O, which is conveyed into the capillaries, unites there with the carbon, forming CO₂, which is exhaled, seized upon by the plant, and in the wonderful laboratory of its cells, the C is separated from the poisonous gas, and retained, while the O is thrown off, again to be used by the fish. Upon the nice adjustment of the plants to the animals, and vice versa, depends the life of both. While upon this subject we might note another interesting evidence of beneficent design in the provision made for both fish and plants.
Water absorbs gases with great readiness—some of them it takes more readily than others; for example, a pint of water will absorb seven hundred pints of ammonia gas. It will take but its own volume of carbonic anhydride under one pressure of the atmosphere.
The descending rain drops absorb these two gases and convey them to the rootlets of the plant, for food. More wonderful still, the Almighty has arranged that water should remove O from the air more readily than it does nitrogen; consequently the rain carries down the O to the fish in river, lake and ocean, adding its life-giving principle to the air, which is always contained in water. It is a pretty sight to watch the breathing of a fish as he sends the rapid currents of water through his gills in the act of aërating the blood, which, as it passes through, gives them a crimson color.
It may easily be proved that plants throw off O, by submerging any vigorous growing plant in a jar of water; in a short time little bubbles will be seen clinging to the leaves; now fill a bottle with water, invert, and touch the little globules gently, when they will detach themselves and pass up into the bottle, displacing the water, and may afterward be used in experimentation. Perhaps some of you, while drinking at the brook, have noted these bubbles of O on the leaves of the graceful water plants below. This is the only place in nature where you can see O free, and indeed you do not see it here, for O is a colorless, tasteless, odorless substance; what you do see is the thin sphere of water which contains it.