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Show [ 8o ] 4· " HENCE in fine .lhca1ns diffufive AcrDs flow, Or wing'd with fire o'er Earth's fair bofom blow; 216 'franrmute to alitterina Flints her chalky lands, b b Or fink on Ocean's bed in countlefs Sands. l-Ienee :Glvery Selenite her cryfial moulds, And foft Afbefius fmooths his :lilky folds ; I-Iis cubic fonns phofphoric Fluor prints, Or rays in fpheres his a1nethyfiine tints. Soft cobweb clouds tranfparent Onyx fpreads, .And playful Agates weave their colour' d threads ; 220 Diffiif:ve Acids flow. 1. 215. The production of marine acid from Jecompo0ng ~ getable and animal matters with vital air, and of nitrous acid from azote and v1tal au·, the former of which is united to its bafis by means of the exhalations from vegetable and animal matters, confl:itute an analogy which induces us to believe that many other acids have either their bafes or are united to vital air by means of fome part of decompofing vegetable and animal matters. The great quantities of flint fane!, whether formed in mountains or in the fea, would appear to deri.ve its acid from the new world, as it is found above the1l:rata of lime-flonc :and granite which confl:itute the old 'v~orld, and as the earthy baits of flint is probably calcareous, a great part of it fcems td be produced by a conjunction of the new and old world ; the recrements of air-breathing animals and vegetables probably afford the acid, and the !hells of marine animals the earthy bafis, while another part may have derived its calcareous part alfo from the decompofition of vegetable and animal bodies. The fame mode of reafuni.ng feems applicable to the filiceous fi:ones under various names, as amethyft, onyx, agate, mochoe, opal, &c. which do not feem to have undergone any procefs from volcanic fires, and as thefe fl:ones only differ from flint by a greater or lefs admixture of argillaceous and calcareous earths. The different proportions uf which in each kind of fl:one may be feen in Mr. Kirwan's valuable Elements "f Mineralogy. See additional notes, No. XIX. [ Sr J Gay piaured Mochoes glow with landfcape-dyes, And changeful Opals roll their lucid eyes ; Blue lambent light around the Sapphire plays, Bright Rubies blu!b, and living Diamonds blaze. 225 " Thus, for attractive earth, inconfiant JovE Malk'd in new ihapes forfook his realms above.- 230 Living DiamQnds hlaze. I. 228. Sir Ifaac Newton having obferved the great power of refracting light, which the diamond poffeffes above all other cryftallized or vitreous matter, conjectured that it was an inflammable body in fome manner congealed. Infomuch that all the light is refletled which falls on any of its interior furfaces at a greater angle of incidence than 24! degrees; whereas an artificial gem of glafs doe~ not refie& any light from its hinder furfacc, unlefs that furface is inclined in an angle of 41 deg. Hence the diamond reflects half as much more light as a factitious gem in fimilar circumfl: ances; to which mufl: be added its great tranfparency, aml the excellent poli!h it is capable of. The diamond had neverthelefs been placed at the head of cryfl:als or prec. ious fl:ones by the mineralogifl:s, till Bergman ranged it of late in the combuflible clafs of bodies, becaufe by the focus of Villette's burning mirror it was evaporated by a heat not much greater than will melt filver, and gave out light. Mr. Hoepfner however thinks the difperfion of the diamond by this great heat fl10uld be called a phofphorefcent evaporation of it, rather than a combuflion; and from its other analogies of cryfta lli zation, hardnefs, tranfparency, and place of its nativity, wi!hes again toreplace it amongfl: the precious fl:ones. Obferv. fur Ia Phyfiqu~:, par Rozier, Tom. XXXV. p. 4+8. See ne\Y edition of the Tr:m!lation of Cront1ed, by De Cofl:a. lnconflant J ove. I. 229. The purer air or ether in the antient mythology was reprefcuted by Jupiter, and the inferior air by Juno; and the conjunaion of thefe deities wa;; faid to produce the vernal fhowers, and procre_ate all things, as is further fpoken of in Canto III. I. 204. I t is now difcovercd that pure air, or oxygene, uniting with variety of bafes forms the various kinds of acids; as the vitriolic acid from pure air and fulphur; PART I. M |
