Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/347

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We shall further illustrate this point, by a brief description of the manner in which the remains of vegetables are disposed in the Carboniferous strata of two important Coal fields, namely, those of Newcastle in the north of England, and of Swina in Bohemia, on the N. W. of Prague.

The Newcastle Coal-field is at the present time supplying rich materials to the Fossil Flora of Great Britain, now

he discovered, thus affording the fullest evidence, if any such proof were wanting, of the Vegetable Origin of Coal.

"Each of these three kinds of coal, besides the line distinct reticulation of the original vegetable texture, exhibits other cells, which are filled with a light wine-yellow-coloured matter, apparently of a bituminous nature, and which is so volatile as to be entirely expelled by heat, before any change is effected in the other constituents of the coal. The number and appearance of these cells vary with each variety of coal. In caking coal, the cells are comparatively few, and are highly elongated.—In the finest portions of this coal, where the crystalline structure, as indicated by the rhomboidal form of its fragments, is most developed, the cells are completely obliterated.

"The slate-coal, contains two kinds of cells, both of which are filled with yellow bituminous matter. One kind is that already noticed in caking coal; while the other kind of cells constitutes groups of smaller cells, of an elongated circular figure.

"In those varieties which go under the name of Cannel, Parrot, and Splent Coal, the crystalline structure, so conspicuous in line caking coal, is wholly wanting; the first kind of cells are rarely seen, and the whole surface displays an almost uniform series of the second class of cells, filled with bituminous matter, and separated from each other, by thin fibrous divisions. Mr. Hutton considers it highly probable that these cells are derived from the reticular texture of the parent plant, rounded and confused by the enormous pressure, to which the vegetable matter has been subject."

The author next states that though the crystalline and uncrystalline, or, in other terms, perfectly and imperfectly developed varieties of coal generally occur in distinct strata, yet it is easy to find specimens which in the compass of a single square inch, contain both varieties. From this fact, as also from the exact similarity of position which they occupy in the mine, the differences in different varieties of coal are ascribed to original difference in the plants from which they were derived. Proceedings of Geological Society. ''Lond. and Edin. Phil. Mag. 3d Series, Vol.'' 2. p. 302 April, 1833.