H. L. Wells — Note on Artificial Sperrylite. 171 



Art. XYII. — Note on Artificial Sperrylite; by Horace 



L. Wells. 



Through the kindness of the Director of the United States 

 Mint, a specimen of artificial sperrylite has been received by 

 the writer, together with an advance copy of an article relating 

 to it, which is to be published in the forthcoming annual report 

 of the Director of the Mint. The article is by Mr. E. J. Wagor, 

 Superintendent of the San Francisco Mint refinery, who en- 

 countered the material and has described- and fully identified it. 

 Through the Director's courtesy, also, permission has been given 

 to make use of Mr. Wagor's article in publishing this note. 



It may be recalled that sperrylite, which was described * by 

 the writer and examined crystallographically by the late Pro- 

 fessor Fenfield, has the composition corresponding to PtAs 2 , 

 that it is the only known natural compound of platinum, 

 and that it occurs in minute, brilliant crystals in the Sudbury 

 region of Canada, in North Carolina, and in Wyoming. 



The artificial substance was prepared in the operation of 

 melting anode mud from the electrolytic cells of the copper- 

 refining process. Mr. Wagor says : " This material will prob- 

 ably average 20 per cent to 30 per cent of the precious metals, 

 including 2 per cent to 4 per cent of platinum, with copper in 

 fragments and powder, sulphate of lead, basic sulphates of anti- 

 mony, bismuth, and tin, sulphides of silver, copper, and iron, 

 arsenates and antimonates, silica, carbon, and fragments of slag. 

 These slimes are washed thoroughly, dried, and melted in cru- 

 cibles with borax and soda and allowed to settle. 



Ct The crystals were found in a very thin layer of speiss which 

 separated from the metal with considerable difficulty. The 

 fact that the crystals are not attacked by acids generally, and 

 only slightly by aqua regia, led to their discovery in the anal- 

 ysis of the speiss. In washing free from acid, it was noticed 

 that the crystals were not easily wet by water, and notwith- 

 standing their high specific gravity, showed a marked tendency 

 to float when brought to the surface of the water ; a marked 

 characteristic of the mineral. 



" The microscope develops striking tin-white, isometric crys- 

 tals with extremely brilliant crystal faces and sharp edges. The 

 crystals are mostly fragmentary, showing cubes, octahedrons 

 and pyritohedrons, and a choncoidal fracture." 



Mr. Wagor gives also the behavior of the substance when 

 heated, which is the same as that of the mineral, and he deter- 

 mined the loss by careful ignition in the air, which accounted 

 * This Journal, xxxvii, 67, 1889. 



