Boston Journal of Philosophy and the Arts; Intended to Exhibit a View of the Progress of Discovery in Natural Philosophy, Mechanics, Chemistry, Geolog (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1824 edition. Excerpt: ...other minerals, hitherto undescribed, if not unknown. Amongst these, the most remarkable are delicate capillary crystals, which are found by the lens to be hexagonal prisms, hollow within, formed by the lateral junction of six long rectangular plates. They are either white, or of a light flesh-red colour, and occupy cavities which seem to have been produced by the total or partial disappearance of the larger crystals of leucite. Acicular radiated mesotype occurs in the same manner, as well as brilliant crystals in rhomboidal dodecahedrons, of a dark green colour. These new crystalline minerals, thus, to all appearance, created out of the elements of a lava composed simply of leucite and.-ingite, during its re-exposure, under peculiar circumstances, to the action of volcanic heat, may be expected to throw a useful light on the origin of the numerous and problematic minerals occurring in those erratic blocks of crystalline limestone, &lc. &lc. of the Monte Somma, which appear to have undergone a similar process during the activity of that ancient and enormous volcano; and a stronger degree of probability is thus added to the opinion, by which these blocks of limestone, with their accompanying mica, augite, vesuvian, nephelinc, &c. &c. are supposed to be, not unaltered fragments of primitive rocks, but portions, perhaps, of the calcareous or other strata which once covered the site of Vesuvius, variously affected by repeated and continued exposur9 to the influence of the mysterious and ever varying phenomena which take place in the fiery depths of the volcanic laboratory. In a chemical light, the eruption of last October distinguished itself from all preceding ones by the excessive abundance of sulphur deposited by the vapours evolved from...