320 ANNUAL OF SCIENTIFIC DISCOVERY. 



earthy matter, in a large number of instances, in a state of solution or fine 

 molecular subdivision. He knows nothing to countenance the supposition 

 that our coal beds are mainly formed of coniferous wood, because the 

 structures found in mother coal or the charcoal layer have not the charac- 

 ters of the glandular tissue of such wood, as has been asserted. It appears 

 that the geological, chemical and microscopical characters of the Torbane 

 Hill coal are similar to those of other cannels, and that the whole evidence 

 we possess, as to the nature of coal, proves it to have been originally a 

 mass of vegetable matter. The only differences which the Torbane Hill 

 coal presents from others are differences of degree, not of kind. It differs 

 from other coals in being the best gas coal, and from other cannels in being 

 the best cannel. 



ON THE OCCURRENCE OF NATURAL COKE IN THE COAL FORMA- 

 TION. 



At a recent meeting of the Boston Natural History Society, Prof. "Wm. B. 

 Rogers communicated some observations recently made by him on the 

 natural coke, and the associated igneous and altered rocks of the Oolite coal 

 region, in the vicinity of Richmond, Virginia. In the district on the north 

 side of the James River, where the most valuable seam of coke has been 

 explored, it is at present wrought by two vertical shafts. In that nearest 

 the outcrop the coke is reached at 112 feet from the stirface, in the other 

 at 207 feet, the dip of the coal measures being nearly west and at a low 

 angle. A third shaft, recently wrought, which lies nearer the margin of 

 the basin than either of the preceding, cuts the stratum of coke at the 

 depth of 90 feet. A bed of whinstone, or coarse gray trap, is intercalated 

 in the coal measures of this part of the basin, intersecting the two first 

 mentioned.shafts, but cropping out a little west of the third. This bed is 

 met with in the deepest and most western of the shafts at a distance of about 

 100 feet from the surface, and is more than thirty feet thick where it is 

 cut through ; but in the next shaft it is at a depth of less than 30 feet, and 

 has thinned down to about half the preceding thickness. 



One of the most remarkable effects produced by this igneous bed is seen 

 in the stratum of carbonaceous fire-clay which lies next beneath. This, 

 which in the second shaft has a thickness of 1 1 feet, has been greatly in- 

 durated and made to assume a columnar structure, by which the whole 

 mass is converted into a congeries of closely-packed five and six-sided 

 prisms, often quite regular, usually about half an inch in diameter, and 

 always at right angles to the lower surface of the trap. 



A portion of this bed, originally occupied by impure coaly matter, 

 presents the same columnar structure, but the material is a compact 

 plumbaginous coke, with much earthy matter intermixed. The general 

 aspect of the gray part of this bed strongly resembles that of the coarser 

 varieties of fire-brick after they have been long exposed to intense heat. 

 This is what might be expected, for in the bed in question we have the 



