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Oriental Topaz. 2 5 x Ir retains its colour and is infufible in a heat öf 170°, fomewhat diicoloured and barely foitened by the heat of pure air. When finely powdered, borax melts it though with difficulty into a greeniüi glafs, it yields alfo to microcofmic falt, but not to fixed aF kalis. By Mr. Bergman’s analyfis, 100 parts ot the vermeille kind contains 40 argill, 39 filex, 10 aeratcd calx, and xoof iron. Ry that ot'Mr. Achard, 41,66 filex, 36,66 ar- g Ul, 8,33 calx, 10,83 of iron. However, I found a compound of 39 parts filex, 40 argill, 10 aerated calx, andiooxyge- nated calx ofiron, tomeltat 14c 0 , into a greyilh black porous flagg. I therefore believe that the proportion of caK fet forth in thefe analyfes too great. The high fpccific gravity of the ftone prevents me from judging that of the iron too high. 2d Family. Oriental Topaz. Its colour golden yellow. Lulfre, 3, 4. Tranfparency, 4. Gives a fin- gle refrattion. Its Ihape as that of the ruby. Its frafture, foliated. Fragments, 3. Ilardnefs, 15. Sp. gr. 4,0106. It is infufible per je, and loles its colour, only in a very high degree of heat. Refills alkaline fluxes,