Stone Coal

Kilkenny Coal and some, of the Swansea Coal (as formerly observed) are of that species vulgarly called Stone Coal; as they burn only when in contact with Bituminous Coal, and then burn a long while, giving a strong heat. The present upper specimen is from Queen’s County, Ireland, and was brought up from the depth of four hundred feet by Mr. Ryan’s patent boring machine^†, which is so conveniently constructed to perforate the earth to a very great depth, through any species of rock that it may be desirable to examine, and thus show the contents solid and undisturbed. It is a neat specimen to show the order of the backs and cutters, which agree with the crystallization, and which should be more attended to in mining for Coal of all sorts: but as the Stone Coal of Wales seldom, or perhaps never, shows these forms so plain as this, I exhibit this as a distinct and curious example. The marking on the upper piece shows signs of the rhombs and hexaëdrons, &c., almost as if laid down from my Plate 2 of Part, I. of Crystallography.

The figure beneath is a specimen broken from an old mine in the same county, showing a similar construction in the rhombs, &c.; and the fragment on the left hand shows the eight-sided figure which happened to break from it at the corner under which it is placed. In it the four rhombic and the four diagonal fractures are very distinct and accurate. These examples show that the smooth Carbonaceous particles of Coal form sometimes as regularly as the Bituminous.

The duller parts are still like fibrous Charcoal, and the brighter partly resemble the bituminous parts of the Newcastle Coal, and can scarcely be distinguished from it without trying its want of inflammability.