HUNTINGTON. — DIAMONDS IN METEORITES. 207 



from the Arva, Novo Urei, or Canon Diablo meteorites. Especially 

 since the work of Daubree and others has shown how numerous the 

 allotropic forms of carbon may be, varying in hardness, specific gravity, 

 aud other physicial characters, it seemed of value to get a more 

 accurate determination of the hardness of this new material, since no 

 distinct crystals had been observed. 



At the suggestion of Mr. George F. Kunz, the author undertook 

 to dissolve many pounds of the Canon Diablo iron, in order to obtain 

 enough diamond dust to use at the Columbian Exhibition for cutting 

 and polishing rough diamonds, thus demonstrating in a practical way 

 the fact that we have true diamonds in meteorites. 



A method of dissolving iron slightly different from that described by 

 the author in " Science"* was adopted, in order to find if possible the 

 paragenesis of the diamond material. About two huudred pounds of 

 the iron was examined, and the most promising pieces were dissolved. 

 The object of working on so large a scale was twofold. In the first 

 place, to obtain sufficient material for the practical test of cutting and 

 polishing rough diamonds, and in the second place to discover how the 

 substance occurred, and whether it crystallized in the usual form. Of 

 course there was also a possibility, though not a probability, of happen- 

 ing upon a crystal of considerable size. The specimens of iron selected 

 were successively suspended by a platinum wire in a platinum bowl, 

 filled with hydrochloric acid nearly saturated with chloride of iron and 

 then slightly diluted with water. The iron was made the positive pole 

 of a battery consisting of twelve gravity cells, the bowl forming the 

 other electrode. When the conductivity of the solution was properly 

 adjusted by means of the chloride of iron it was found that only the 

 pure iron of the meteorite would dissolve, thus setting free the plates 

 of schreiberseit and taenite, as well as the graphite and other impuri- 

 ties, bringing out the crystalline structure of the meteorite in wonder- 

 ful perfection. 



A partially dissolved piece is shown a little less than the natural size 

 in Figure 1. Unfortunately, the sketch does not bring out the plates 

 as prominently as they appear in the specimen, and the differences 

 of tint, which are very striking in the original, cannot be reproduced in 

 a black and white print. If the acid was too strong, or the temper- 

 ature of the solution slightly increased, all the distinction of parts at 

 once disappeared, and it dissolved en masse, leaving a great quantity 

 of slime in the bottom of the dish. 



* Vol. XX. No. 492, July 8, 1892. 



