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j 72. Muriati'c Genus. But is faid to be infufible in the flrongeft heat of our furnaces. According to the anaiyüs of Mr. Hoepfner, it contains 0,47 filex, 0,38 aerated magpefia, 0,04 argill, 0,02 aerated calx, and 0,09 iron. 2oth Speeles, Cpmbined with the Boracic Acid, and boracited Calx. Boracite *. Colour, greyifh white, fometimes paffing into the greenifh white, orpurplifh. Hitherto it has been found only in cubes, whofe angles have been more or lefs deeply cut off. Their fize fcarcely exceeds an inch. The furfaces generally fomewhat corroded. The external luftre, if the furface be fmooth, 3; if rough o. Internal, greafy, 2. Tranfparency (except it be covered with an opake rind) 2. 3. Trafture, compad, and of the fmall flatted conchoidal kind. Fragments 3. L'ardnefs, 9, 10, Sp. gr. 2,566. Expofedtothe flrongeft heat, it contra&s, and at laft melts into ayellowifh glafs. It does not efferveice nor diflolve in acids, v^n- lefs heat be applied, * * Bergm. Joiirn. 1790.234. z An. Chy. 102, 137* 3 bcrl. Beobacht x. Abbe