probably among the causes of their comparative barrenness.[11]

In these qualities are found the mechanical relations between earths and vegetables. To the divisibility of the former it is owing, that the latter are enabled to push their roots into the earth; to their density, that plants maintain themselves in an erect posture, rise into the air, and resist the action of the winds and rains; and to their power of absorbing and holding water, the advantage of a prolonged application of moisture, necessary or useful to vegetable life. But besides performing these important offices, there is reason to believe that they contribute to the food of vegetables. This opinion rests on the following considerations and experiments:

1. If earths do not contribute directly to the food of plants, then would be all soils alike productive; or in other words, if air and water exclusively supply this food, then would a soil of pure sand be as productive as one of the richest alluvion.

2. Though plants may be made to grow in pounded glass, or in metallic oxides, yet is the growth, in these, neither healthy nor vigorous; and,

3. All plants, on analysis, yield an earthy product;[12] and this product is found to partake most of the earth that predominates in the soil producing the analyzed plant; if silica be the dominant earth, then is the product obtained from the plant silicious; if lime prevail, then is the product calcareous, &c. &c. This important fact is proved by De Saussure.

1st Experiment.

Two plants (the pinus abies) were selected, the one from a calcareous, the other from a granitic soil, the ashes of which gave the following products;

2d Experiment.

Two Rhododendrons were taken, one from the calcareous soil of Mount de la Salle, the other from the granitic soils of Mount Bevern. Of a hundred parts, the former gave fifty-seven of carbonate of lime and five of silica; the latter, thirty of carbonate of lime, and fourteen of silica.

3d Experiment.

This was made to determine whether vegetables, the product of a soil having in it no silica, would, notwithstanding, partake of that earth.—Plants were accordingly taken from Reculey de Thoiry, (a soil altogether calcareous) and the result was a very small portion of silica.

These experiments, says Chaptal, leave little if any doubt, but that vegetables derive the earthy matter they contain from the soil in which they grow.[13]

2. Of water, as an agent in vegetation.

Seeds placed in the earth, and in a temperature above the freezing point, and watered, will develope; that is, their lobes[14] will swell, their roots descend into the earth, and their stems rise into the air. But without humidity, they will not germinate; or deprived of humidity after germinating, they will perish. When germination is complete, and the plant formed, its roots and leaves are so organized as to absorb water. The experiments of Hales prove, that the weight of plants is increased in wet and diminished in dry weather; and that in the latter, they draw from the atmosphere (by means of their leaves)[15] the moisture necessary to their well being.—Du Hamel (and after him Sennebier) has shown, that the filaments that surround the roots of plants, and which has been called their hair, perform for them in the earth, the office that leaves perform in the atmosphere, and that if deprived of these filaments the plants die.

It would be easy, but useless, to multiply facts of this kind tending to establish a doctrine not contested, but which after all does not assert, that water makes part of the food of plants. On this point two opinions exist—the one, that this liquid is a solvent and conductor of alimentary juices: the other, that is itself an aliment and purveyor of vegetable food at the same time. The first opinion is abundantly established. Water when charged with oxygen, supplies to germinating seeds the want of atmospheric air, and saturated with animal or vegetable matter in a state of decomposition, or slightly impregnated with carbonic acid, very perceptibly quickens and invigorates vegetation. The second opinion is favoured by some of De Saussure's experiments. On these, Chaptal makes the following remark, which expresses very distinctly an approbation of the doctrine they suggest:—"The enormous quantity of hydrogen (which makes so large a part of vegetable matter) cannot be accounted for but by admitting (in the process of vegetation) the decomposition of water, of which hydrogen is the principal constituent; and that though there is nothing in the present state of our experience that directly establishes this doctrine, yet that its truth ought to be presumed, from the analysis of plants and the necessary and well-known action of water on vegetation.

(To be continued.)

Correction.—In copying the second section, page 55, an error escaped in relation to the Tuscan plough; the passage should have read thus—"The plough of the north of Europe, like that of this country, has the power of a wedge, and acts horizontally—that that of Tuscany has the same direction, but very different form. With the outline of a shovel, it consists of two inclined planes, sloping from the centre, and forms a gutter and two ridges.

Review for the Rural Magazine.

An Expose of the Causes of Intemperate Drinking, and the means by which it may be obviated. By Thomas Herttell of the city of New York. Published by order of the New York society for the promotion of internal improvement.—New York, 1819.—pp. 56.

This is an ingenious and interesting pamphlet. It is written with much force and originality; and we think we