This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1880 edition. Excerpt: ...half-a-dozen more delicate hues; some coarse, some fine as Samian ware; the rocks themselves were composed of an almost glassy substance, strangely jumbled, even intercalated now and then with soft sand. This, we were told, is a bit of the porcellanite formation of Trinidad, curious to geologists, which reappears at several points in Erin, Trois, and Cedros, in the extreme south-western horn of the island. How was it formed, and when? That it was formed by the action of fire, any child would agree who had ever seen a brickkiln. It is simply clay and sand baked, and often almost vitrified into porcelain-jasper. The stratification is gone; the porcellanite has run together into irregular masses, or fallen into them by the burning away of strata beneath; and the cracks in it are often lined with bubbled slag. But whence came the fire? We must be wary about calling in the Deus e machina of a volcano. There is no volcanic rock in the neighbourhood, nor anywhere in the island; and the porcellanite, says Mr. Wall, "is identically the same with the substances produced immediately above or below seams of coal, which have taken fire, and burnt for a length of time." There is lignite and other coaly matter enough in the rocks to have burnt like coal, if it had once been ignited; and the cause of ignition may be, as Mr. Wall suggests the decomposition of pyrites, of which also there is enough around. That the heat did not come from below, aa volcanic heat would have done, is proved by the fact that the lignite beds underneath the porcellanite are unburnt. We found asphalt under the porcellanite. We found even one bit of red porcellanite with unburnt asphalt included in it. May not this strange formation of natural brick and China-ware be of immense...