208 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The iron was dissolved in two- or three-ounce pieces, and it at once 

 appeared that there was a wide variation in its composition. Most of 

 it contained no diamonds whatever. One piece, however, in the pro- 

 cess of dissolving showed an irregular vein running through it consist- 

 ing of a white vitreous substance varying in width from a fine line to 

 nearly four millimeters. On trying the hardness of the vein-stuff, it 

 was found to be beyond the ruby. On further examination, it ap- 

 peared to be a mixture of iron, a sulphide of iron, silica, amorphous 

 carbon, and diamond, so that it finally had to be crushed in order to 

 get rid of all the iron. 



The hardest grains were isolated by the method described in the 

 previous papers, and when examined under the microscope one minute 



but perfect octahedron of diamond was found, transparent and col- 

 orless. It was separately mounted on a microscope slide, but soon 

 disappeared, and in its place were found only some very minute 

 angular fragments. A second crystal was afterwards isolated, but dis- 

 appeared in like manner, suggesting that they had been formed under 

 pressure, and when exposed in a warm room had exploded. 



This called to mind the fact that broken diamonds are so often 

 found in the South African mines, though the cases may not be 

 analogous, since in the latter instance the fragments have never been 

 found associated. 



About half a carat of diamond powder was finally obtained, being 

 separated by its specific gravity from a very large quantity of amor- 

 phous carbon. The particles varied from colorless through yellow 

 and blue to black. Many of them appeared to be angular fragments, 

 though some of them looked not unlike hyalite except for their more 

 brilliant lustre. Several perfect little octahedrons were found that did 



