Volltext Seite (XML)
DIAMOND. 5 rather inclines to semitransparent; but the black variety is nearly opaque: ami it refracts single. Hard in the highest degree; it scratches all other known minerals. Rather easily frangible. Rather heavy, approaching heavy. Specific gravity 3.518, Cronstedt.— 3.521, Muschen- brocck.—3.521, Wallerius.—3.500, Brisson.—3.600, Wer ner.—3.5195 to 3.55, Haiiy.— 3.51 to 3.53, Brong.— 3.488, Lowry. Constituent Parts. Roetius de Boot, in his History of Gems, published in 1609, conjectured that the diamond was an inflammable substance. In 1673, Boyle discovered, that when expo sed to a high temperature, part of it was dissipated in acrid vapours. In 1694 and 1695, experiments were made in the presence of the Grand Duke of Tuscany, which confirmed those of Mr Boyle, and shewed that the diamond, although the hardest of minerals, agrees with combustible bodies, in being combustible. In 1704, Sir Isaac Newton, in his great work on Optics, hinted, that trom its very great refracting power, it might be an unc tuous substance coagulated *. Since that period, the diamond has been very often examined by chemists, and they find, that when heated to the temperature of 14° of Wedgwood’s pyrometer, or not so high as the melting point of silver, it gradually A 3 dissipates • Newton docs not appear to have lwen acquainted with the experiments made in Tuscany; and, besides, a considerable part of his work on Optics was written in 1675.