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' DißinSlive Characlers. 41 fpecific gravities of many minerals are given that were never before examined, as well as of a great number that had been examined, but not in all their varieties. Mr. Werner, though he recommends an accu- rate determination when it can be obtained, di* vides in general all minerals into 1 fupernutant, that is, that float on water. z° light, viz. thofe whofe fpec. grav. extends from 1, to 2,000. 3 not nmarkably heavy, whofe fpec. grav. extends from 2,000 to 4,000. 4 0 heavy, whofe fpec. grav. extends from 4, to 6,000; and 5° very heavy, whofe fpec. grav. exceeds 6,coo. 'I his grofs de- termination may be learned by long experience of weighing them in the hand. The moft convenient inftrument for taking fpec. gravities is that invented by Mr. Nichollbn, of which a defcription mav be feen in vol. II. of the Memoirs of Manchetler, or Mr. Magellan s improved edition of Cronlledt. When the fpec. gra/. of any ftone \s much inferior to that of the fpccies to which it other- wife feems to belong, it were proper to reduce it to powder, and take its fpec. grav. in that üate alfo. Adhesion to the tongue and fingers, Colo 7 r of a flreak, Diffusion in water, are eafily under- ftood. As to the Ff.el, we mav diftinguifh thofe that are rough, Jmooth, or greajy. The Smell may be fuljyhureous, bituminous, urinous, or earthy. The Taste aßrin^ent, faline, &c. As to the R. E F R. I GERATING POWER, thit IS, of imprcffing a fenfation of cold when feit, though in general it is too vague to deferve notice, yet in fomc particular inftances it may be ufeful to oblerve