Viscous Bitumen

This is a nearly fluid variety of Bitumen; it exhibits the various tints, from the greenish brown to the rare amber colour, sufficiently, we expect, for illustration. The green may be seen in a liquid state in a phial, at the British Museum, and I have figured the solid tureen variety tab. 137. all those varieties occur occasionally from the running or liquid state to the hardness of Asphaltum, but of a tougher texture, between Asphaltum and hard leather.

The upper specimen is so soft, that a trifling touch separated some of the bubbling part, exposing the greenish interior, and the other parts retain their bubbled and liquid running like appearance, as if merely a little hardened by exposure to the common air, and if kept in a moderate temperature in a drawer will probably continue as it now is for ages. It is as usual on a variety of Limestone, that occasionally holds Vitiate of Lime, Sulphuret of Lead or Galæna, remains of shells, Entrochi, &c. The lower specimen is of the hardness and texture of the softest India rubber, of a more amber colour, and is rather scarce: the Fluate of Lime and stone as usual. They are brought from Castletown, the usual locality. The lower left hand specimen is somewhat magnified to show the irregular structure. The green coloured specimens generally appear orange by transmitted light, which is the reason why the thinnest parts of the specimen above appear of that colour, but the lower specimen is so transparent, that it appears of an orange brown, with very bright reflections.