cate leaves and ferns, with their parts in perfect preservation, and nowise crumpled; on observing the reeds quite straight and in their primitive position, we conclude that all these plants could not have been much drifted and tossed by the waters, but that they now lie near their native bed. In what degree the action of sulphuric acid, or sulphate of iron, producible from the pyrites so generally distributed in coal measures, has contributed to the conversion of wood into coal, we have no satisfactory data to determine. Mr. Hatchett has furnished some ingenious speculations on this subject.

The quantity of ammonia which coals afford in distillation, has led some chemists to suppose that they are at least in part, a product of the decomposition of animal bodies. It is possible that these may have contributed slightly; but when we see several plants, such as the cruciform family, yield ammonia, we need not press the argument for its animal origin. The bituminous schist of Thuringia which contains so great a quantity of fishes crushed and even converted into a species of coal, and which is occasionally used for fuel, demonstrates the possibility of that carbonaceous transmutation. The coal of Pomiens in Dauphiny yields on distillation a large quantity of ammonia. It contains numerous sea shells, and even bones of marine animals, to which probably some of its substance is due. But as this does not occur in a genuine coal-formation, it cannot be regarded as a true pitcoal. It is clear, however, that animal matters are convertible into something very like coal.

VAST ACCUMULATION OF CARBON.

169

That carbonaceous matter is also an original constituent of the mineral kingdom, is sufficiently obvious from the existence of plumbago, or nearly pure carbon, in the middle of gneiss, mica-slate, and other primitive rocks. Anthracite or stone coal, is found disseminated in the quartz and barytes of the metallic veins of Kongsberg; localities where it cannot be ascribed to the decomposition of vegetables. Besides what a vast magazine of carbon, is locked up in limestones, under the form of carbonic acid?

To the vegetable origin of the coal-measures, the great quantity of carbon contained in them appears a formidable objection. In spaces of no large extent, 30, 40, or even 60 strata or seams of coal, occur separated by layers of sandstone and schistose clay. Could this succession have been possible had the plants remained in the place of their growth? Whence could proceed at regular intervals that quantity of herbaceous plants, which has produced the 61 seams of the coal basin of Liege?

We must bear in mind, however, the vigour of vegetation that prevailed in these latitudes on the antediluvian globe. Of this fact, the fossil vegetables now found in our coal measures are ample testimonials. See Book III. Chap. iii.

The phenomena of basaltic veins and beds, penetrating all the strata, even the chalk or cretaceous limestone, prove that during the whole interval from the creation to the deluge, the antediluvian ocean, under which these basalts were generally protruded, must have experienced violent agitations, which would throw up the waters over its shores, and

sweep down with the reflux, the prolific vegetation into their sandy bed. Here the high temperature of the seas, indicated by the fossil remains of crocodiles and turtles now found in our shell strata, would rapidly decompose the submersed plants, into a bituminous paste, where it would be soon covered with a layer of sand. In this way we may imagine how coalmeasures even to the extent of Liege or Newcastle, may have found successive beds of vegetable material, during the period that elapsed between the creation and the deluge. We must not however limit to that interval the conversion of the buried vegetable bodies into coal; for unquestionably that coal might go on progressively ripening during many subsequent ages by aqueous percolation.

One of the richest deposits of coal that is known, forms the nearly continuous series of coal basins placed in a belt about 150 miles long and 6 miles broad, which crosses the north of France, containing the coal-mines of Valenciennes, Condé, Mons, Namur, Liège, &c. They produce annually more than 70 millions of quintals of coals, worth 30 millions of francs, and they employ 35 thousand colliers. Their beds have a direction similar to that of the band; they are of an uniform nature, accompanied with the same sandstones and schistose clays. They present similar foldings, and every thing indicates that they are parts of one whole, which extends beyond the Rhine to Osnabruck. The coal-mines in the neighbourhood of Newcastle, put out annually more coal than the whole of the above French district, namely, 2,355,000 London chaldrons according to Mr. Winch.

LOCALITIES OF COAL.

171

M. Villefosse, in his Traitè de la Richesse Minerale, estimates at little more than double the above amount the product of all the coal mines of England; a quantity certainly too small.

Germany contains several great deposits of coal, particularly in Thuringia, and its neighbourhood, in Saxony, Bohemia, and Silesia. Coal is very rare in the north of Europe, in Sweden and Norway; countries so rich in mines of other kinds. Spain and Italy possess almost none.

Coal exists in China in considerable quantity; and perhaps there is no country in the world, richer in coal than the provinces of Chensi, Chansi, and Petcheli, says M. Panser, in his Mineralogy of the Chinese Empire.

Mr. Maclure informs us that to the west of the Alleghanys, there is a formation of coal most extensive and regular. Its beds are from one to six feet thick; and are placed to the number of 20 or 30 over each other. They alternate with sandstones, schistose clay, and clay containing iron ore.*

That the mountain limestone beneath the coal of the English mines, has been a marine formation, is perfectly evident from the nature of the imbedded shells. But the vegetable organic remains of the coal-measures themselves indicate that their strata have been deposited out of the sea, most probably under a fresh-water lake. The inferior limestone stratum may therefore have been raised by subjacent expansive force, before receiving the succession of vegeto-carbonaceous, sandy, and clayey deposits. But since the coal measures are covered in many places with marine strata to a considerable depth, the sea must have once more inundated that marsh land, converting it into an estuary. Successive inundations consentaneous with the successive submarine eruptions of trap, which are known to have occurred about that geological period, seem capable of explaining the phenomena of alternate deposits, and of accounting for the introduction among the coal measures

As the origin of our coal-fields must obviously be sought for in antediluvian vegetation, the reader will find the subject amply discussed in Book III. Chap. iii. of this work.

Lignites which are manifestly bituminized wood, hold an intermediate place in the gradation between vegetable matter and pit-coal. They have the fibre of the former, with the jetty lustre and fracture of the latter. Some lignites closely resemble peats in their chemical characters, others seem to graduate into perfect coal. It is therefore the geological position in the coal measures, that defines this combustible. Whatever is found in the strata above the magnesian limestone has been called a lignite. Coal is in fact to vegetable matter, what adipocire is to animal; the completion of the chemical change, in which the fibrous structure disappears. Lignite has generally a woody aspect; coal always that of a rock.

Lignite appears in three distinct localities; in alluvial soils, among traps, and under stratified rocks. Marine remains occur in all the lignites; showing their beds to have been formed by drifted wood under the sea; whereas they are very rare in true coal. Hence one is led to infer that the coal-basins have been originally lakes liable to alternate inundations; whence the alternate deposits of vegetable

themselves, of a few sea fossils, the bottom of the estuary being of course nearly level with the ocean. That such eruptive violence accompanied and followed the coal formations is placed beyond a doubt, by the multitude of dislocations and dykes, which traverse the coal-fields in every direction, and by the basaltic caps thrown over them, as at the Corstorphine-hills near Edinburgh.-Macculloch-Journ. Science, No. 44. p. 312.