642 North and Conover — Mineral Sulphides. 



Molybdenite and Cobaltite. — These two minerals were not 

 affected by the reagent even after heating for several days. 



Orpiment and Realgar. — These minerals were completely 

 dissolved by thionyl chloride within a few hours. No attempt 

 was made to identify the arsenic trichloride formed inasmuch 

 as it is a liquid and difficult to separate from thionyl chloride. 

 Reaction had certainly taken place, as was shown by the sul- 

 phur dioxide and sulphur monochloride which were easily 

 identified in the tubes. 



Stibnite. — This mineral likewise was completely dissolved 

 by the reagent, undoubtedly with the formation of antimony 

 pentachloride. The tube contained sulphur dioxide and sulphur 

 monochloride, leaving no doubt that reaction had taken place. 



Sphalerite. — No visible change took place in the sphalerite, 

 but after heating for several days the solid contents of the tube 

 were shown by analysis to be zinc chloride. Reaction there- 

 fore had taken place. 



Tetrahedrite. — Tetrahedrite was found to react slowly with 

 the formation of anhydrous cupric chloride. The antimony 

 and sulphur went entirely into solution. 



Arsenojpyrite. — Arsenopyrite was completely decomposed 

 after heating for a few hours, the arsenic going entirely into 

 solution while the iron remained in the form of crystallized 

 ferric chloride. 



Resume. — Of the minerals studied, the only simple sulphides 

 which do not -react with thionyl chloride are argentite and 

 molybdenite. In general the more complex mineral sulphides 

 and sulph-arsenides are likewise decomposed by the reagent 

 though the time required for complete reaction varies greatly. 



Eutgers College, New Brunswick, N. J. 



