with that of the avater, the hydrogen of which combines with the. rest of the sugar, and forms alcohol.

In my memoir On the Cause of Chemical Proportions, I mentioned organic substances as of a composition difficult to be explained by the views of the corpuscular theory. We see that in proportion as we study organic nature these difficulties disappear; and in the present state of our knowledge the corpuscular theory is the only one which puts it in our power to explain the composition of organic atoms in a satisfactory manner. I shall probably discuss the subject more at large hereafter; when furnished with a greater number of experiments I shall be able to speak about it with more confidence,

ARTICLE IV.

An Essay on the Shapes, Dimensions, and Positions of the Spaces,

in the Earth which are called Rents, and the Arrangement of the Matter in them. By Mr. John B. Longmire.

(Continued from p. 92.) The Arrangement of the Matter in Bended-Tabular Rents. The most of bended-tabular rents contain matter which is similar to that of the formation in which they exist ; but some of them contain matter very different to it. Hence in treating of the matter in these rents, a very natural arrangement is to divide them into such as contain matter which proceeded from that contiguous to them, and such as have been filled with matter that entered them at the earth's surface. Again, as the matter in all bendedtabular rents which contain matter similar to that of the formation in which they exist is arranged in the shape of tabular masses accompanied with crystals ; and sometimes with variously shaped masses confusedly mixed together; and as all the rents which contain tabular masses contain earthy tabular masses, but only some of them metallic tabular masses, I divide them into those which contain earthy, and into those which contain earthy and metallic tabular masses.

FIRST DIVISION.

The Arrangement of that Matler in Bended-Tabular Rents which

has proceeded from the Matter on the Sides of these Rents. 1. Of the Matter in Rents containing only Earthy-Tabular

Masses. In bended-tabular rents filled with earthy matter only, but which has proceeded from the matter of the formation in which these rents exist, two sorts of earthy-tabular masses are found. The

masses of one sort vary in denomination as do the strata; but those of the other are generally of one denomination throughout a rent, and their arrangement is very different from that of the first sort. These masses I divide, for reasons which will afterwards appear,

into the first-formed and second-formed tabular masses.

of the First-Formed Tabular Masses. The first-formed tabular masses are known by the names of veinstones, ribs, walls, &c. In the parts of these rents where the first-formed tabular masses exist very regularly arranged, the following order is observed. If A Al, fig. 1, Plate XXXII., be a stratum of coal, in the rent H I a tabular mass of coal G is so situated that its under side m d lies between two lines d, m, one parallel to and opposite the line which joins the surfaces of separation be to the under side ef, and the other parallel to and opposite the line l, and its upper side ai is similarly disposed towards the lines 0, h, as is its under side towards the lines è, l. If the stratum B B i be slate-clay, it has a tabular mass of slate-clay n in the rent, similarly situated with respect to it, as the mass G is to the stratum A Al; the stratum C, and every other stratum in the rent above the stratum A, has a tabular mass arranged in the same manner as the masses G 0; and the strata D, E, F, and all the strata below them, have tabular masses h, q, r, &c. which are similarly disposed. But all the masses differ as much from one another in external characters, as the strata from which they proceed differ from one another.

The arrangement of the first-formed tabular masses is seldom so regular as it is here represented : for sometimes there are many small tabular masses between the surfaces of separation of the strata, as fe, fig. 2,' represents. These masses are sometimes at great distances from one another, in the horizontal direction of the rent, and very small; but as we proceed horizontally towards the centre of the masses, as in the direction al, they increase in dimensions, and at the centre, as at l, there is one large mass, which perhaps fills the whole height, and a considerable distance horizontally. Beyond this mass they decrease in dimensions, and as the distance from it increases, the distance from one another increases also; till at last they become what miners aptly call “grimings." Beyond this place, as beyond c, we find no more of these masses for a considerable distance cd; they then begin again, increase and decrease in magnitude as before.

The arrangement of the first-formed masses, as just described, is very perfect in all small rents of this shape; but in the larger it is seldom perfect.

The first-formed tabular masses, as I said before, resemble the matter contiguous to the rents in which they are situated; so that in the coal formation they consist of alternations of coal, slateelay, white sand-stone, &c.; in the red, and white sand-stone, of red and white sand-stone; in lime-stone, of lime-stone;

and in granite, gneis, sienite, &c. of these rocks respectively.

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When we see these tabular masses lying in a rent of the coal formation, between the surfaces of separation of the strata on the sides of that rent whose matter is the same as theirs; when in addition we recollect, as before stated, that these masses in granitic rents are granite, &c. we are irresistibly led to the conclusion that these masses are a part of the matter which existed in the formations before these rents took place; because had they proceeded either from above or below, they could not have assumed their present "

highly inclined positions ; " nor is it probable that they would be similar to the matter near the rents; and it is still less probable that where the matter of a formation consists of strata of different denominations, these masses would lie close to strata whose denominations are similar to theirs. These remarks are sufficiently conclusive : but there is one fact still which gives them greater weight, and that is, that parts of the coal from which these masses are supposed to proceed, are wanting to such distances from these rents, that the area of the parts wanted is about equal to that of the large masses in the rents. Therefore I think the position, that the matter thus arranged in rents proceeds from the matter which is contiguous to them, is fully proved.

The process by which these masses have acquired their present situations and positions may have been similar to that which is described as follows. After the formation of the separated surfaces of the stratum in which the lowest extremity of a rent is situated, the parts of that stratum which were still in a fluid state passed naturally into the rent, or were forced into it by the incumbent weight as the rent gradually increased in width. Several parts of the strata close to the rent would be fluid, therefore near the whole of it was filled opposite these parts ; in other parts only small portions of the strata were fluid, of course only small parts entered the rent; and in other parts the strata were sufficiently solid to resist the weight of the incumbent matter, so that from these parts no matter was forced into the rent. It is easy to conceive that such a modification in the arrangement of the masses as that already described would take place in this manner. From the angular position of the masses in a bended-tabular rent, and from the other phenomena already described respecting them, I deduce the formation of the rent in the stratum opposite its lowest extremity so long before its commencement in the second stratum as to allow the matter which entered the rent from the lowest stratum to be so much consolidated, that it would retain its position as the rent continued to widen, and would support the fluid matter which rested on it when the formation of the rent in the second stratum from the bottom commenced; and the commencement of the rent's formation in

l every stratum, reckoning upwards, before its commencement in that stratum which rests on it, such a length of time as I have mentioned to take place between the commencement of the rent's formation in the lowest stratun, and of its commencement in that stratum which lies on it.