- Class 1. Combustibles.
- Order 3. Mixed.
- Gen. 1. Bitumen.
- Syn. Retinasphaltum. Hatchett in Phil. Trans. for 1804. 410.
This very inflammable substance would, by its usual appearance, be taken for dark Umber while wet, and for common Clay when dry; consequently there is nothing in its common appearance that would indicate its inflammability or resinous quality. Very nice discrimination is therefore requisite to comprehend it. To the touch, however, it in some measure indicates a resinous quality.
Mr. Hatchett, who first mentioned it in Linn. Trans, v. 4. 139, observes that “a yellowish brown compact substance, which in colour and fracture somewhat resembles ferruginous clay, is round occasionally with the Bovey Coal. It is brittle, and is highly inflammable; it melts like Bitumen, and emits a smoke which in smell resembles Amber. This substance is but rarely found.” He also observes, in the Philosophical Transactions for 1804, p. 402, that “it is found in pieces of a moderate size. The fracture is imperfectly conchoidal. It appears earthy externally; but when broken exhibits, in a slight degree, a vitreous lustre. The fragments are irregularly angular, and completely opaque at the edges. It is extremely brittle. It does not apparently become softened when held some time in the hand, but emits a faint resinous odour . The specific gravity at a temperature of 60° of Fahrenheit is 1.135. When placed on a heated iron it immediately melts, smokes much, burns with a bright flame, and yields a very fragrant odour, like some of the sweet-scented resins, but which at last becomes slightly tainted with that of asphaltum. The melted mass, when cold, is black, very brittle, and breaks with a glossy fracture.”
By the analysis of 100 grains by Mr, Hatchett it appears to contain:
I had the pleasure of receiving this, with a valuable series of the wood passing to the most perfect Bovey Coal, from Bovey Heath field, near Chudleigh, Devonshire, by favour of Dr. Beeke.