Bitumen, or Petroleum

Mineral Oil or Petroleum which seems in arrangement to precede the Elastic Bitumens, is found in turf near Ormskirk tit Lancashire, and in the debris of broken rocks at Pitchford in Warwickshire. I have it also from Colebrook Dale in Shropshire, and from Derbyshire among Hie Elastic Bitumens; but this latter may not strictly be the same as the others: for although found in the hollows, &c. of Carbonate of Lime, it seems in that district to belong to the Elastic sort accompanying it, although no difference is otherwise perceptible.

The present variety becomes rather darker and apparently less limpid on exposure to the air, is of a brown black colour, not elastic, soils very much, sticking worse than common Tar, and requires much grease to expel it. It runs slowly in a warm temperature. Its odour is stronger than the other Mineral Bitumens, but of the same nature. It is the origin of the famous British Oil said to be of such wonderful efficacy in the bills of the Patentee of Shrewsbury.

The upper figure represents a piece of sandy rock impregnated with Petroleum, with fragments of Schist or Slate. The lower figure represents a mass of Sandstone, with the Petroleum also; and the few dark splashes are small points of common bituminous Coal. By heating these the Petroleum may be made to run out in a perfect state, or it may be obtained by distillation.