Page:Theophrastus - History of Stones - Hill (1774).djvu/211

 other Foils: The other they have in common with Stones; and, indeed, with almot all other foile Bodies whatever. It was impoible for our Author to have known this, unles he had had our Aitances. But we find by Experiments with powerful Burning-glaes, that in a manner all foile Subtances, as well as Earths, are fuible and vitrifiable.

Earths, determinately peaking, are opake Bodies, diffuible by Water, and vitrifiable by extreme Heat; friable when dry, not inflammable, and generally inipid to the Tate: Not that thee are certain, univeral Characteritics, and liable to no Exceptions. Whatever may be the Cae in the Vegetable and Animal Kingdoms, it is the Misfortune in the Study of foile Bodies, that uch has been the Confuion and Intermixture of their contituent Particles at the general Deluge, that there are none uch to be etablihed in them; for there are o many heterogene Particles, of a thouand different Kinds, mixed even with the ame Foil in different Places, that there is no determining to any Certainty, even its Manner of Variation from its pure State. What I have given may pas, however, for a general Character of what, in Treaties of Foils, we mean by the Word Earths; which may be afterwards ditinguihed into Clays, Ochres, Boles, Marles, Chalks, and Loams. Sand, and the common vegetable Mould, which ome give a Place in the Catalogues of Earths, have of right no Buines among them; for the firt is only either a maller kind of Gravel, coniting of an infinite Number of mall Pebbles of different Shapes and Colours; or the contituent Particles of the Stone of Strata or other Bodies accidentally looe: and the latter owes its preent Mode of Exitence, in a great meaure, to putrifed animal and vegetable Subtances of a liquated, altered from its original State and Conitence, and afterwards indurated again, It will melt, as Stones, with fuible and foile Subtances; and is oftened, and made into Bricks: Thee are of various Kinds, and compoed in various Manners, but are all made by moitening and burning.