- Class 1. Combustibles.
- Ord. 1. Homogeneous.
- Gen. 6. Carbon.
- Spec. 2. Oxygenized Carbon.
- Gen. Char. Hardest of all known substances.
- Spec. Char. Carbon conbined with such a proportion of oxygen as to remain in a solid state, mostly opaque black.
- Syn. Native Mineral Carbon. Kirw. 2. 49*.
We find Mr. Kirwan’s description of Native Mineral Carbon*, Blende-Khole† of Werner, so well agrees with the Denbigh coal, that the chief part of his expressions may with great propriety be made use of. His specimen, he observes, is the purest known, and came from Florence; it depends much upon the choice of specimens to cull the purest; and in the same mine many varieties may be found. There is little doubt of the Denbigh coal being nearly as pure an oxide of carbon as is likely to be found. “Its colour is black; its lustre from 3 to 4, approaching the metallic. Transparency 0. Hardness 4 to 5: brittle: stains the fingers.” It could only be the softer part occasionally found in this coal that stains the fingers; as in that from Swansea, resembling charred wood; dusty and with less lustre than above-described‡, and what he denominates Culm coal of Wales; another variety which agrees with what Werner calls Glanz-Khole.
Denbigh coal is seldom stratified, and is apt to separate with a reedy structure, or impression, in regular striæ. The cross fracture is often conchoidal and undulating. This fracture and the prismatic hues for which this coal is famous, have, have naturally gained it the appellation of Peacock coal; and it is no less remarkable, that a piece with the colours on it, may be heated red hot many times, and, on cooling again, will return to nearly the same appearance, retaining its prismatic hues.
We are happy to say Mr. Jameson promises to give a fuller account of his khole-blend, at some early opportunity, and has also primised, with his usual generosity, to supply us with specimens. All coals commonly so caled produce black powder.
- * When Mr. Kirwan wrote this, common charcoal was thought to be pure carbon; it is since found to be an oxide of carbon, and that Diamond is the only native mineral carbon known. Mr Kirwan’s description agrees with oxide of carbon, for which we quote him.
- † Mr. Jameson calls this Khole-Blend, and observes that it does not stain the fingers.
- ‡ This, when irregular an dloose, as it sometimes is, appearas by the description to be the smut of this author. Culm means only smallish coals of inferior value, which to not pay duty.