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Compaä LmeßonS. 81 VJith many of thefe colours tcgether in blotcbes, Veins, ftripes, or fpecks. i It frequently abotiods with impreflions or pe- trifadions of mnfcle?, fnails, corals, peftinites, gryphites, mytulites, &c. Its luftre o, or barely i, from ä few fhining particles; its tranfparency o, rarely 2. Its frac- ture compäd, moft commonly fplintery, coarfe Or fine, rarely pafling to the cönchoidal; fome- times uneven, fometimes eartüy, rarely Jflaty. Its fragments 2. Its hardnefs from 5 tö 8, rarely 9 *, except mixed with quartz. Its fpec. grav. 1,3864 (before abforption of water) to 2,72. Thofe that have their fpec. gr. below 2,4 äre eXceeding pofous. Effcrvefces with acids, and thus lofes from 0,38 to 0,42 of its weight. Bdrns W Üme. Dr. Higgins has remarked that limeftones kept ever fo long in a red heat lofe only 4 of their weight; in a heat that melts cop- per they lofe about and in a heat that melts taft iron, that is, from 120° to 130° Wedgwood, they lofe as much as they can lole, that is, from 38 to 44 per ct. All thefe ftones contain fome flight cotitami- nation from other ftones, argill, or iron,amounting nt moft to about 10 or 12 per ct.; if more than 13 the limeflone is fo notably dcgradcd as fcarceiy to afTord lime, and fhould then be exeluded from the fpecies we here confider; thefe contamina- _ * Mr. Anderfon, in a valuable traft on limeßones, men- tions lome foiind in Sunderland, which in exrernal appear- ance rtlemble ilinrs, and R ive firc with ftccl, yet burn to lime as pure as that of chalk. li%s on Agriculture, vol. If. P* l88, G tions