or split, save in one case, where such was foreseen by M. Daniels: a stone evidently composed of two diamonds joined together, upon the first application of heat broke with considerable violence into two fragments, each constituting a decided crystal.... All that took place in the crucible could be distinctly seen through the sheet of mica, and thus ample evidence was obtained that the diamond, while in a state of combustion, is surrounded by a small flame, the exterior envelope of which is a violet-blue, similar to that produced by oxide of carbon in a state of combustion. “This is especially the case when the diamond is rather large, when the lamp has been withdrawn and the platinum has ceased to glow; the diamond is then seen upon the black ground of the crucible, brilliant with vivid white light, and surrounded by a zone or aureole somewhat less bright, its exterior edge being a blue-violet color. Some highly interesting microscopic observations relative to the dull surface of diamonds which have undergone partial combustion have been communicated by Mr. G. Rose; he has discovered on them regular triangular markings that resemble those occurring in abundance on the fine crystals from the Vaal River, and recall the faces formed on planes of crystals, soluble in acid, by the slow and imperfect etching action of such a re-agent, as, for example, the action of hydrogen chloride on calcite. Like them these depressions on the diamond bear an exact relation to its crystalline form, and are determined by certain definite faces, their sides being parallel to the edges of the octahedral faces of the crystal. Measurement with the goniometer shows them to belong to the icositetrahedron, the faces of which have not been met with on diamond. These symmetrically shaped pits can easily be seen by heating a thin plate of boart in a blow-pipe flame and examining it under the microscope. “By prolonged heating several small triangular pits will often merge into one large one. A crystal of diamond, even when so reduced in size by oxidation as to be only visible with difficulty, continues to exhibit sharp edges and angles. A dodecahedron, with very rounded faces but smooth and brilliant surface, also exhibited the triangular pits often very distinctly; moreover, it had a brown color, which was not destroyed by heat, and must therefore be of a totally different nature from that of the topaz or smoky quartz.” The above copious extracts by no means exhaust the very interesting and valuable particulars to be found in the article, and I would advise all interested in the matter to purchase this issue of the magazine, if still in print, and read for themselves.