202 



BULLETIN 42, UNITED RTATES NATIONAL MUSEUM. 



and immediately takes on water aud I'ouus tsulpliuric acid (H2SO4) 

 This chamber acid contains a large excess of water which must be 

 evaporated to i)roduce the strong acid or oil of vitriol. The process is 

 practically the same whether sulphur or pyrite is used, except that in 

 the hitter case there is a large residue of oxide of iron left in the fur- 

 nace after the combustion of the sulphur. Five characteristic specimens 

 of pyrite are shown : 



(1) Iron pyrite, coutaiuing, chalcopyrite, blende, and qnartz. Coarse ore. Char- 

 lemont Mine, Franklin County, Massachusetts. (54144.) 



(2) Iron pyrite, fine ore. Cliarleiiiont Mine, Franklin County, Massachusetts. 

 (54145.) 



(3) Iron pyrite, containing about 50 per cent, of sulphur. Granular ore. Arminius 

 Sulphur and Copper Mine, Tolersville, Louisa County, Virginia. (54239.) 



(4) Iron pyrite, containing about .50 per cent, of sulphur. Lump ore. Arminius 

 Sulphur aud Copper Mine, Tolersville, Louisa County, Virginia. (54242.) 



(5) Iron pyrite with chalcopyrite, contains about 50 per cent, of sulphur. Lump 

 ore. Arminius Sulphur and Copper Mine, Tolersville, Louisa County, Virginia. 

 (54241.) 



The Arminius ores show on analysis : 



Sulphur (S) 



Iron (Fe) 



Copper (On) 



Zinc (Zn) 



Lime (CaO) 



Magnesia (MgO) 



Arsenic (As) 



Silica (SiOj) 



Oxygen (0) 



THE MANUFACTURE OF SULPHURIC ACID FROM IRON PYRITE. 



This process is illustrated by a collection from the Merriinac Chemical 

 Works, Boston, Massachusetts. 



Ore. 



(1) Iron pyrite, containing a little quartz and calcite. Lump ore. Davis Mine, 

 Charlemont, Franklin County, Massachusetts. (.55457.) 



(2) Iron pyrite, granular ore. Davis Mine, Charlemont, Franklin County, Massa- 

 chusetts. (55458.) 



(3) Roasted, the residue remaining after the sulphur has been burned off from the 

 Davis ore, contains about one and one-quarter per cent, of copper. (55459.) 



Products. 



(1) Chamber acid, dilute sulphuric acid made from Davis ores. (55460.) 



(2) Oil of vitriol, or concentrated chamber acid, made partly from the Davis ore and 

 partly from brimstone. (55461.) 



