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sient blaze. Were a few houses in a large city set on fire, such would be the rapidity with which the flames would spread on every side, that in a few hours, or even minutes, the whole city would be wrapped in one wide and unquenchable blaze, and no human art could arrest the progress of the destructive conflagration. In such atmospheric air, iron would be calcined, instead of acquiring from the fire that softness necessary for forming it into various instruments; it would accelerate to a dangerous degree the circulation of the fluids in animal bodies, and produce a degree of heat through the influence of which they would rapidly waste and decay. We know by experience that nitric oxyde, which consists of forty-four parts of nitrogen and fifty-six of oxygen, produces instant suffocation in all animals that attempt to breathe it. We also know that the nitric acid, one of the most corrosive substances, is composed of seventy-five parts oxygen and twenty-five parts nitrogen, which are only different proportions of the substances in atmospheric air; so that were the atmosphere conposed of the same proportion of ingredients, our breathing it might produce the same effect as if we were to swallow a pint of aquafortis, or nitrous acid, which we all know would produce our immediate destruction. Can we, then, be at a loss to perceive, in the adjustment of the gases which compose our atmosphere, the wisdom and benevolence of the Deity; and, at the same time, the infinite comprehension of the Divine

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Mind, in foreseeing all the effects that would be produced by the different combinations of these gases, and in selecting that particular combination for the atmosphere which is precisely adapted to the existence and the comfort of living beings ?

2. The Divine wisdom and goodness are no less conspicuous in determining the relative specific gravity of these gases. The oxygen gas is found to be a little heavier than common air, and the nitrogen a little lighter, which enables it to rise to the higher regions of the atmosphere. In respiration (or breathing) there are four stages or periods:-1. Inspiration, or drawing in the air.—2. A pause when the lungs are filled.-3. Expiration, or breathing out the air from the lungs;—and 4. A pause when the lungs are emptied. In breathing, the air which is evolved from the lungs at every expiration, consists chiefly of nitrogen, (and a small portion of carbonic-acid gas,) which is entirely unfit to be breathed again, and, therefore, by its levity, rises above our heads before the next inspiration. The pause which takes place between every inspiration is evidently intended to allow time for the nitrogen gas which is thrown out of the lungs to rise in the air, in order that a fresh portion of the atmosphere may be taken in, and that the same air may not be breathed again. During that remarkable interval, there is time left for the noxious fiuids to separate, the nitrogen to ascend while the carbonic-acid gas preponderates,

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leaving a space between for a fresh current of pure atmospheric air to rush into the lungs. But what would be the consequence if nitrogen gas, instead of being a little lighter, had been a slight degree heavier than common air, or of the same specific gravity ? Then we should not only have been obliged to breathe a portion of it again at every inspiration, but the vast quantity of it thrown off by the respiration of men and other animals would have perpetually occupied the lower regions of the atmosphere; and especially in our chambers it would have accumulated to such a degree as to have produced diseases, pestilence, and death, in rapid succession. But, being a little lighter than the surrounding atmosphere, it flies upwards, and we never breathe it again till it has entered into new and salutary combinations. Such is the benevolent skill which the great Author of nature has displayed for the preservation and comfort of the human race, and of every species of animated existence.

3. The wisdom of the Creator is displayed in the process for supplying the waste of oxygen, and promoting the renovation of the atmosphere. The quantity of carbonic acid which is daily formed, by combustion and the respiration of animals, is so great, that it must have rapidly increased to a most dangerous extent., had not the Almighty provided means for its being as rapidly decomposed. It is well known that whenever atmospheric air becomes charged with one-tenth of this gas, it is unfit for

promoting combustion, and is fatal to most animals that breathe it. Hydrogen too, and carburetted hydrogen gas, are perpetually evolved at the surface of the earth from various sources, particularly from marshes, dunghills, and stagnant pools; and these are likewise prejudicial, and even destructive, to the animal creation. On the other hand, oxygen gas, which is the support of fire and animal life, is continually wasted by the various processes of combustion, as in the case of furnaces, burning candles, and domestic fires, and by the breathing of all animals. How, then, has the all-wise Creator contrived to supply this waste, and to protect the inhabitants of the world from the baneful effects of the other gases with which the atmosphere is contaminated ? The

process appears to be this:-Vegetables are so constituted that carbon and hydrogen are the necessary food of plants, and are - conducive to the support of vegetable life. Their vegetating organs seize the carbonic-acid gas that comes within their reach, and while they appropriate the carbon to themselves, the oxygen is thrown off to renovate the atmosphere, by its union with the nitrogen ejected by animal respiration. The leaves of trees, shrubs, and other vegetables, give out, during the day, a large portion of oxygen gas, which unites with the surrounding air, keeps up the equilibrium of the gases, and preserves the salubrity of the atmosphere; for it is found by experience that the air in every region, in the most crowded cities, as well as

INVISIBILITY OF THE ATMOSPIIERE.

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in the open fields, contains the same quantity of oxygen gas. Thus it appears, that what is noxious to man is rendered beneficial to the vegetable tribes, and the oxygen of which they do not stand in need, is separated by them, in its utmost purity, for the use of man.

The wisdom, the simplicity, and the beneficence of this arrangement, cannot fail to produce conviction in every reflecting mind, that the laws of nature are not to be referred to blind chance, but to unerring intelligence combined with boundless beneficence. In every breath draw, we may perceive, if we reflect on the above-stated arrangements, that we are every moment indebted to an all-wise and almighty Being in whom we live and move, for the continuance of our existence and for every comfort we possess, and therefore praise, adoration, and thanksgivings, are due to him from all the ranks of his intelligent offspring.

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The department of the subject already treated, may now be concluded with a reflection or two, founded on the statements previously made.

1. From the invisibility of the atmosphere, and its numerous and important effects in the system of nature, we may learı the folly of denying the reality of a future and invisible state of existence, because the objects connected with that state are not perceptible by our corporeal senses. Who could have imagined, previously to modern discoveries, that all the

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