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CHAPTER II.

SUMMER.

SUMMER arrives, the sun attains its zenith of splendour and heat, and under its influence the buds and blossoms of Spring have transmuted into foliage and flowers; they adorn and diversify the scenery of the earth; they captivate our senses, by their exquisite structure, and their delicious fragrance; they all exert specific functions upon surrounding media, for maintaining the harmony and order of the Creation; let us therefore resume our investigation regarding vegetable growth.

The seed weighed only a few grains, when cast into the earth in Spring; it has now produced a plant, weighing many ounces, and the general increase of bulk which has ensued throughout the vegetable kingdom, cannot fail to elicit a remark from the most listless observer let us endeavour, if possible, to account for this growth upon chemical principles.

If the chemist undertake the ultimate analysis of a vegetable, or the generality of vegetable products, for example, Lignin or woody-fibre, Sugar, and Starch, he finds them to yield nearly half their weight of Oxygen and Hydrogen in the proportions requisite for the constitution of Water; and nearly half their weight of Carbon; this will be evident, upon reference to the tabular statement at pages 21 and 22 of the Introductory Chapter.

Now the dry timber, or lignin, or woody fibre, of an average sized oak, weighs about Sixty tons, and therefore it contains about Thirty tons of Carbon.

Again, Europe alone, annually consumes about Five hundred thousand tons of Sugar, containing about Two hundred and fifty thousand tons of Carbon. It therefore becomes a curious question, as to the source of the enormous quantity of this solid element Carbon; for the chemist discovers, upon close examination of the earth in which vegetables grow and flourish, that it loses no considerable weight, as the following account of an experiment will prove.

Two hundred pounds of earth were dried in an oven, and afterwards put into a large earthenware vessel; the earth was then moistened with rain-water, and a willow tree, weighing five pounds, was planted therein.

During the space of five years, the earth was carefully watered with rain water, or pure water; the willow grew and flourished; and to prevent the earth from being mixed with fresh earth, or dust blown upon it by the winds, it was covered with a metal plate, per

forated with a great number of small holes, suitable for the free admission of air only.

After growing in the earth for five years, the willow tree was removed, and found to weigh One hundred and sixty-nine pounds, and about three ounces; the leaves which fell from the tree every autumn were not included in this weight.

The earth was then removed from the vessel, again dried in the oven, and afterwards weighed; it was discovered to have lost only about two ounces of its original weight; thus, One hundred and sixty-four pounds of lignin 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 eightyfour 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,