Iron and the hardness of Carborundum. 471 



being made the positive pole and the dish the negative pole of 

 a Bunsen cell. The iron was slowly dissolved, leaving on the 

 cone a large amount of black slime. This was carefully col- 

 lected, digested over a steam bath for many hours, first with 

 aqua regia, and afterwards strong hydrofluoric acid. A con- 

 siderable part of the residue disappeared, but there remained 

 a small amount of white grains which resisted the action of 

 the acids. These particles, when carefully separated by hand, 

 had the appearance of tine beach sand. Under the microscope 

 they were found to be transparent and of brilliant luster. One 

 of the grains was then mounted upon a point of metallic lead, 

 which, when drawn across a watch crystal, was found to give 

 the familiar singing noise characteristic of a glass cutter's tool 

 and with the same result, namely, cutting the glass completely 

 through. It deeply cut glass, topaz, and a polished sapphire. 

 These facts, first announced in Science, &pril 8, 1892, were 

 presented at the meeting of the American Academy of Arts 

 and Sciences on May 11, 1892, and were published in the Pro- 

 ceedings of this Academy, new series vol. xxii, pages 252-253. 



Later M. C. Friedel says in the Bulletin de la Societe Fran- 

 caise de Mineralogie,* that he took a fragment of the Cafion 

 Diablo meteorite weighing 34 grams, which gave the charac- 

 teristic Widmannstattian figures, and treated it with hydro- 

 chloric acid. He digested the residue in aqua regia and ob- 

 tained a black powder. After various treatments he thus 

 separated about "35 gram of a powder which he presented to 

 the Academy. The powder sank in a solution of the iodide 

 of methyl having a density of 3*3. JS"o grains measuring more 

 than *5 mm to '8 mm were found, the powder being fine and impal- 

 pable, capable of scratching corundum. He also burned some 

 of the black residue, and as a product obtained CO Q . 



At the meeting, above referred to, of the Academy of Arts 

 and Sciences, Dr. Huntington showed to the members, under a 

 microscope, the slightly yellow transparent grains he had ob- 

 tained, and called attention to their adamantine luster. Not 

 enough of the clear material was obtained at the time for a 

 chemical test, and, on account of the association of the dia- 

 mond grains with amorphous carbon, such a test would not 

 have been conclusive without a perfect mechanical separation. 

 One of us (G. F. Kunz) suggested that, if enough of the clear 

 grains could be obtained to polish a diamond, it would con- 

 clusively prove that the material was diamond. For this pur- 

 pose about 200 pounds of the meteoric iron was carefully 

 examined, and specimens which appeared to contain diamonds 

 were dissolved. The method used will be published by one of 



* Xo. 9, p. 258, Dec, 18^2. 



