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or greenish brown to the light red brown, and is easily compressed ; 
but sometimes the same piece is less elastic in one part than another. 
On burning it, the smell is rather pleasant. 
The varieties of this fossil, described by Mr. Mawe, are— 
1. Elastic bitumen, of a reddish brown colour, containing nodules of 
indurated shining black bitumen, resembling jet.— 2. A piece in a 
marine shell, in lime-stone. — 3. Dull, red, and transparent, in crys- 
tallized fluor.— 4. Composed of filaments, like soft cauk, and of a 
singular acid taste. — 5. Indurated amorphous masses and globules of 
a shining black, like jet; sometimes liver-coloured; electric, when 
rubbed. — 6. With asphaltum, and containing red ore ; and the same 
in long filaments, almost as fine as wire. 
A considerable spring of petroleum exists at Colebrook Dale. 
This spring was discovered at about thirty yards in depth, whilst 
digging to form an archway to convey the coals from a very deep 
pit. It was at first found to ooze from between the brannies of the 
rock, but soon began to pour out in a considerable stream, running 
even into the Severn. Large iron pipes are employed for the con- 
veyance of the. fluid into proportionably sized pits, which have 
been sunk for its reception. Hence it is conveyed into immense 
caldrons, in which it is inspissated, by boiling, to the consistence of 
pitch. Whilst fluid, the tar, which appears to be remarkably free 
from impurity, has rather an agreeable odour ; and when inspissated, 
it exactly resembles the asphaltum of the Dead Sea. Since its first 
discovery, three different springs of it have broken out, one of 
which pours out a considerable quantity. Near to the celebrated 
iron bridge, this bituminous fluid is emitted pretty copiously, being 
almost pellucid, but thicker than treacle. A similar rock with that 
from which the petroleum flows may be traced upwards of seven 
miles ; the coals, which are found at some depth beneath the petro- 
leum, are of an exceeding good quality. 
