TO H. L. Wells — Sperrylite, a new Mineral. 



ness in hydrogen. In its behavior with solvents and its pyrog- 

 nostic properties the artificial compound agrees exactly with 

 the natural mineral. 



Method of analysis. — The amount of substance taken for 

 each analysis was about 1*5 g. The pulverized substance was 

 gradually heated in a current of chlorine gas and the volatile 

 chlorides were absorbed by water in a receiver.* This liquid 

 was made ammoniacal after adding a very small quantity of 

 tartaric acid to keep the small amount of antimony in solution 

 and the arsenic was determined as magnesium pyroarseniate. 

 From the filtrate from the ammonium magnesium arseniate, 

 antimony and a trace of platinum were precipitated as sul- 

 phides, the sulphide of antimony was dissolved in strong hydro- 

 chloric acid, the sulphide was reprecipitated, filtered on asbes- 

 tus and weighed after proper heating in a current of carbon 

 dioxide, while the trace of platinum sulphide was ignited and 

 the residue was added to the main part of the platinum left by 

 treatment with chlorine. This part was treated with dilute 

 aqua regia ; this left an insoluble residue consisting of cas- 

 siterite and a finely divided black substance which had been 

 found by previous qualitative tests to be rhodium. This resi- 

 due was fused with sodium carbonate and sulphur, the insolu- 

 ble rhodium sulphide formed was ignited in air, then in 

 hydrogen and weighed, while the tin was determined as stannic 

 oxide in the usual way. The purity of the rhodium was shown 

 by its complete solubility in fused potassium disulphate, also 

 by finding that it gave no sodium double chloride soluble in 

 alcohol after ignition with sodium chloride at a faint red heat 

 in a current of chlorine. About § of the total rhodium was 

 found here. The purity of the stannic oxide was shown by 

 reducing it in hydrogen and dissolving the metal in hydro- 

 chloric acid. 



The solution in aqua regia containing platinum with a little 

 rhodium and iron and a trace of palladium was treated for the 

 platinum metals essentially by the method of Glaus ;f the main 

 variations being a repeated separation of platinum from rhod- 

 ium and the weighing of platinum as metal. A distinct but 

 extremely small precipitate of palladium cyanide was obtained, 

 but the amount of palladium was too small to sensibly affect 

 the balance when an attempt was made to weigh it. 



The name. — The writer takes great pleasure in naming this 

 interesting mineral after Mr. F. L. Sperry, to whose efforts this 

 investigation is due. 



Sheffield Laboratory, Dec. 12, 1888. 



* Preliminary experiments with the artificial compound, PtAs 2 , had shown that 

 all the arsenic passes off in this operation if the heat is applied slowly enough 

 so that the substance dees not melt after losing a part of its arsenic 



f Rose und Finkener, analytische Chemie, 6 te Aufl., vol. ii, p. 2 :6. 



