nin or woody-fibre, bark, roots, &c., were certainly produced, but from what source?

Why, the chemist who made this remarkable experiment, in very early days of scientific investigation, reasonably concluded the tree to have derived the increase of its structure from water alone, as no other source was obvious; and the opinion that water was the sole aliment of vegetables, was entertained by many of the greatest philosophers; but as knowledge regarding the powers and properties of matter throughout the Creation, became gradually extended by experiment, the Air was discovered to be the source of the solid element at least, which enters into the structure of the vegetable kingdom.

This statement may at first appear incredible, but upon slight reflection, its truth is proved, because the Air, or atmosphere, contains Carbonic acid, and it is a Compound of 714 parts by weight of Oxygen, and 286 parts by weight of Carbon.

By means of several inorganic agents, having an intense affinity for Oxygen, the chemist can decompose Carbonic acid, and obtain its solid elementary Carbon; but he discovers, that the leaves of vegetables under the influence of vitality, effect the decomposition, with a degree of refinement and precision perfectly inimitable, by his utmost skill; in fact, that they withdraw, and secrete into their structures, Carbon from Carbonic acid, and liberate pure Oxygen.

Still the young student may ask,-Although this curious compound called Carbonic acid, does exist in the air, is it in sufficient quantity for the supply of Carbon to constitute half the weight of trees, shrubs, plants, herbage, and the endless variety of vegetable clothing

that now adorns the earth, and likewise the important proximate principles obtainable from these?

The experienced chemist, in reply, states, that there is abundance of Carbonic acid for this purpose, naturally existing in the air, its weight being expressed by the enormous sum of Five trillions, two hundred and eighty-seven billions, three hundred and five millions of TONS.

In other words, the number for expressing this quantity of Carbonic acid, vastly exceeds that for expressing the number of SECONDS which have elapsed since the Creation, namely, one hundred and eighty-four billions, four hundred and fifty-four millions, one hundred and fifty thousand, and four hundred!

In addition to the enormous weight of Carbonic acid, just stated, it must be remembered, that the respiration of man and animals, the processes of combustion, the phenomena of the germination of seeds, the ripening and the decay of fruits, the putrefaction of organic matters, are hourly sending forth incalculable quantities of the same compound into the atmosphere.

In fact, the chemist can only determine with tolerable accuracy the weight of the quantity of carbonic acid exhaled by human beings; and when this is done, it strikes the mind with wonder and amazement, at the stupendous scale upon which natural phenomena proceed, under the guidance of Omnipotence.

The volume or bulk of Carbonic acid produced by a healthy adult individual in twenty-four hours, amounts to about fifteen thousand cubic inches, containing about two thousand six hundred grains of Carbon, or about six ounces, or to between thirty-seven and thirty-eight pounds, from every hundred persons; so that, assuming

thirty seven-pounds as the average, one million of human beings would thus exhale into the surrounding air, a compound containing no less than three hundred and seventy thousand pounds, or upwards of one hundred and sixty-five TONS of Carbon!

The total population of the globe is estimated at Seven hundred and sixty millions; and accordingly, on the above data, they would exhale Carbonic acid, containing one hundred and twenty-five billions, and four hundred millions of TONS of Carbon!

"If there were not excellent, and adequate adjustments, which compensate for, and virtually remove, this poisonous effluvium of Carbonic acid,-for poisonous it must be called in reference to its abstract effect upon the animal system, as mentioned at page 27,-it would soon overwhelm us ;" and we have indeed occasion to extol the power and goodness of God, when we discover the miraculous workings which He has ordained, for the disposal and uses of the agent we are considering.

In the first place, Carbonic acid is a vapor,-escaping from the lungs in a heated state, by which it gains wings, as it were, and is instantly wafted away; in the next place, it has what is termed "diffusive property, meaning the power of uniformly blending with the enormous volume of the atmosphere, so as to elude detection. in hurtful quantity; and lastly, as most particularly applicable to the present inquiry, "this carbonic acid, which is poison to us, is the food of plants, and of the whole vegetable world; they absorb it into their systems, and whilst they retain the Carbon they emit the Oxygen, and so feeding themselves, they purify our Atmosphere."

"Here, then, the Chemist reveals the mutual depend

ence of the animal and vegetable kingdoms," and presents for our admiration and gratitude a magnificent example of the power and goodness of God,-" Who hath created nothing in vain; and Whose tender mercies are over all His works."

This miraculous process of the analysis, or decomposition of Carbonic acid by the vegetable kingdom, appears to be constantly active, though certainly in the greatest degree, under the direct influence of solar light; and it admits of most satisfactory illustration by simple experiments.

Provide a quart wide-mouthed stoppered bottle, of flint-glass; remove the stopper, and apply a slight touch of pomade to its ground part, and likewise to that of the neck of the bottle; replace the stopper, turn it gently round twice or thrice, to distribute the pomade thinly and evenly between the ground surfaces, to make an air-tight joint; then again remove the stopper, and pour in a few spoonfuls of water.

Kindle a wax-taper, attached to the end of a bent wire, as in the experiment described in page 67; introduce this into the bottle, and keep it there until the flame ceases; then withdraw the extinguished taper, and quickly introduce a sprig or two of growing mint; lastly, in

sert the stopper, tie it over with a string, that it may not be forced out by expansion, and then place the bottle in the sunshine the arrangement is here represented.

The combustion of the taper in the confined portion of the air, has withdrawn the greater portion of its oxygen, and formed carbonic acid, and liberated nitrogen; the rays of the sun will excite the leaves of the mint to decompose the Carbonic acid, to secrete its Carbon and to liberate Oxygen, which, blending with the unaltered Nitrogen, will restore the contents of the bottle to their original condition; this fact is proved by removing the stopper after a few days, and again introducing the lighted taper; it will then burn, as it did at the outset of the experiment.

If a portion of air be vitiated by respiration, as in the experiment described at page 69, upon introducing a few sprigs of mint into the glass, and then exposing the arrangement to sunshine, a similar result will be obtained.

:

Sprigs of mint are directed to be used in these experiments, as they were the simple means by which this important discovery was originally made, as follows:A chemist found that air was not vitiated by the growth of a sprig of mint, kept in it for some months; he therefore thought it possible that the process of vegetation might restore the air injured by burning candles; accordingly he put a sprig of mint into air in which a wax candle had burned out; and ten days afterwards he found that another candle burned perfectly well in it; and then to verify the conclusion, he divided the injured air into two separate portions, putting the plant into one of them, and merely leaving the other; he always found that a candle would burn in the former, but not in the latter.