472 Kunz and Huntington — Diamonds in Meteoric Iron. 



us (O. "W. Huntington) later. After enough material had 

 been separated by Dr. Huntington, on Monday, September 11, 

 1893, through the courtesy of Messrs. Tiffany & Co., we were 

 enabled to try the desired experiment in their diamond cutting 

 pavilion in the Mining Building of the World's Columbian 

 Exposition, they having prepared a new skaif or wheel, meas- 

 uring 10J inches in diameter, which was placed in position, 

 the wheel having been specially planed down and prepared 

 with the radiating scratches so as to be easily charged with 

 diamond powder. A diamond was then soldered in a metal 

 dopp and placed on the clean wheel, which made 2,500 revo- 

 lutions to the minute. This diamond was tried for more than 

 five minutes by itself without the slightest polish being pro- 

 duced, and no markings other than such as would be produced 

 by the minute shattering of the diamond at extreme edges, due 

 to the friction, as when a diamond is placed on an uncharged 

 wheel. At 9 : 20 a cleavage, weighing five thirty-seconds 

 of one carat was set with solder in the metal dopp which was 

 placed on the wheel. The diameter of the wheel where the 

 diamond was to be placed was four inches. The wheel was 

 then charged with the residue from the meteorite (the powder 

 mixed as usual with oil). The moment that the diamond was 

 placed on the wheel a hissing noise was apparent, showing to 

 an expert that the material was really cutting the diamond. 

 At 9 : 23 a flat surface measuring 3 mm by l mm had been ground 

 down and polished. At 9 : 30 a small crystal with a natural 

 face up was set in the metal dopp, the crystal being a small 

 natural complex twin weighing four thirty-seconds of one carat. 

 It was first tried on a projecting angle. The cutting was very 

 slow for a time, as the natural face of a diamond is always ex- 

 ceedingly hard. The position .of the stone was then slightly 

 changed, and a face measuring 2 mm by l mm was ground on the 

 stone and cut. Three minutes later the surface had been cut 

 down somewhat and a decided polish was produced on the tri- 

 angular face, which was 3 mm by 125. The fragment used was 

 one of the octahedral faces of a crystal. The face ground 

 down was at the angle of 45 degrees with the octahedral face. 

 The entire time of this experiment was 15 minutes. The two 

 experiments having been made with great care with both of us 

 present, we cannot hesitate to pronounce the material diamond 

 or a substance with the same hardness, color, luster and bril- 

 liancy. 



In August last, one of us (G. F. Kunz) while exam- 

 ining the hardness of u carborundum," a carbide of silicon, 

 made by Mr. Acheson of Pittsburg,* it was found that it 



* See Engineering and Mining Journal . 



