"

pably, the inorganic substances which every kind of grass requires for its clothing; it leads him to reason upon this, and to mingle silica and potash with soils in which they are not naturally abundant; and thus, under Providence, the next consignment of seed to the earth, may germinate and flourish in greater perfection and luxuriance, and yield at the season of maturity a greater and more valuable harvest than even that of which a portion was destroyed.

The chemist proves the same facts to be even more importantly applicable, as regards the growth of corn, for he discovers the beautifully smooth and polished clothing of its straw, consists of silica naturally withdrawn from the soil, in company with potash, and elaborated by the wonderful vital functions of the plant.

This silica, by its flinty hardness, and its insolubility in water, shields the soft organic tissue of the straw from the depredations of insects, and protects it from the solvent action of rain; it likewise confers strength and elasticity upon the tissue which alone would form a weak and fragile stem, enables it to support the weight of the full ear, permits it to bend beneath the passing blast, and causes it to recover an erect position in the tranquil air, that its maturity may be promoted by the rays of the glowing sun.

Silica is nearly absent from the ear of corn, but the earthy compounds already mentioned as phosphate of lime and phosphate of magnesia, are invariably present in considerable proportion; and if these substances, together with potash, do not naturally occur in soils intended for the growth of corn, they must be artificially added by the agriculturist, or a full harvest can never be obtained.

Sandy and calcareous soils are generally deficient in potash, and are unfruitful in grasses and corn; but turneps and other plants which require but little of such compound, will thrive exceedingly well; on the other hand, clayey, or argillaceous soils, are very abundant in potash, and accordingly are fruitful in grasses and corn.'

The agriculturist is aware that successive crops of wheat cannot be advantageously grown upon the same soil; the chemist points out the reason of this, namely, that the potash of the soil becomes exhausted; and he proves that wheat crops, of all others, are the most exhausting; for example, one hundred pounds of wheatstraw, when burned, will generally yield fifteen pounds of ash or cinder; whilst the same weight of barley straw will yield but nine pounds, and of oat straw only four pounds. The growth of beans and of beet demands none of the earthy compounds which are so imperatively requisite for that of wheat and other grain.

The insolubility and permanence of the silicious clothing of straw, point it out to the husbandman as the best natural material for covering hay-stacks and corn-ricks in the form of thatch.

Long unbroken straw is selected for this purpose, as it is water-proof, and allows the rain to trickle freely from its surface; but broken straw will not answer, because its silicious clothing is full of fissures or capillary channels, which would receive and retain a considerable portion of the rains of Autumn, or the snow waters of early Spring, and soon become rotten and useless as a protection against further inclemency of weather.

A thick layer of good thatch is a covering not only water-proof, but of exceedingly imperfect conducting

power, equally preventing the sudden penetration of heat and cold; thus in Summer, ice may be prevented from thawing by covering it thickly with straw; and in Winter, fruits may be preserved from frost by similar means.

The "bungalows" of India are built with baked or unbaked bricks, and they are generally thickly thatched, to prevent the transmission of heat; so are tents likewise protected from sun and rain by a straw thatch laid on frames of bamboo.

The limit prescribed for this general investigation concerning the phenomena of the Four Seasons, which admit of elucidation through the science of Chemistry, now demands the conclusion of this Chapter, relating to a few only of those which are presented during the beautiful season of Summer, and throughout it, whilst humbly considering, and endeavoring to explain the manifold and "wondrous works" by which we are surrounded, we have been inevitably led to extol the power and goodness of "The Great Workmaster."

"He that created the heavens and stretched them out; He that spread forth the earth, and that which cometh out of it; He that giveth breath unto the people upon it, and spirit to them that walk therein."

Numberless phenomena remain veiled in impenetrable mystery to all men, and regarding such, the lowly-minded and true lovers of wisdom" make a full confession of their ignorance; but, unhappily, examples are numerous, of men proudly assuming the title of "philosophers," and so greatly estimating their own abilities, as to be ready, not only to explain everything, but dogmatically to state what MUST be the physical cause of everything, in the vast and perfect laboratory of Nature,

as if they were explaining the machinery, and demonstrating the motive power, of a work made with hands.

These are not "philosophers;" nor have they the remotest claim to the title, as they are deficient in its leading attribute, humility, for "Hardly do we guess aright at things that are upon earth; and with labor do we find the things that are before us."

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CHAPTER III.

AUTUMN.

"HE changeth the times and the seasons." He now ordains the reign of Autumn to commence, accompanied by the glorious sun, still shedding brilliancy and heat, for the advancement of the productions of the earth to the mature and bounteous harvest, the hope of which has so long cheered the husbandman throughout his anxious toils.

Many extraordinary and beneficial natural phenomena, several of which may be elucidated through the science of chemistry, are frequently presented in an equal degree during the end of Summer and the beginning of Autumn; these will accordingly now demand our attention; and in the first place, let us direct it in continuance of the investigation concerning the miraculous provision that is made to prevent the earth from the accumulation of a withering and destructive intensity of heat.

We have already found that the earth is capable of absorbing heat, though incapable of conducting it to any considerable extent; we shall now discover that the earth has likewise the power of parting with an excess of heat by radiation towards the unclouded Summer and Autumnal skies.

The meaning of the term "radiation" may be thus explained: suppose the circle in the centre of the annexed