110 BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



chloride. The solution coutaiuiiig copper is theu left for some time in 

 contact with scrap wrought iron, which reduces the copper to the me- 

 tallic state, while the sesqui-chloride of iron is reduced to the proto- 

 chloride and is ready to be used over agaiu. 



In the cases of oxides and carbonates of copper, and some silicates, 

 like chryoscolla, the process can be applied directly, but some of the 

 silicates have to undergo a previous treatment before the process cau 

 be applied. Sulphide ores of copper are crushed and roasted to con- 

 vert the coi)per into oxide and sulphate before treatment. This process 

 is applicable to all ores of copper, except such as contain large amounts 

 of the carbonates of lime, magnesia, or zinc, and is especially applica- 

 ble to silver-bearing copper ores. 



The process was formerly carried on by the Chemical Copper Com- 

 pany, Phoeuixville, Chester County, Pennsylvania, and is illustrated 

 by the following specimens : 



Ore. 



(1) Chalcopyrite, with some silicates aud carbonates of copper, and magnetite; 

 sulphide ore. This ore comes from the copper-bearing portion of a large deposit of 

 magnetite which is mined for iron smelting. It contains 3 to 4 per cent, of copper, 

 and 30 to 50 per cent, of iron. Jones Mine, Berks Conuty, Pennsylvania. (5157.) 



(2) Clay, containing copper, also traces of zinc and nickel; silicate ore. This ma- 

 terial forms great beds underlying the magnetite ores, and contains about 4 per cent, 

 of copper. Jones Mine, Berks County, Pennsylvania. (11673.) 



Intermediate products. 



{1} Sulphide ore, crushed to pass a screen of fifteen holes to the linear inch, ready 

 for roasting. Contains about 3 per cent, of copper. (51o'.'.) 



(2) Roasted sulphide ore, after passing through a three-hearth reverberatory fur- 

 nace. It contains 1.45 per cent, of copper in the form of oxide; 1.25 per cent, in the 

 form of sulphate, and 0.30 per cent, in the form of unoxidized sulphide. (514S.) 



(3) Residue, left after treating the roasted ore with solution of ijroto-chloride of 

 iron and salt and washing. It still contains about 0.40 per cent, of copper, mostly as 

 sulphide. (5153.) 



(4) Concentrates, obtained by washing the residues. Contain about 67 percent, of 

 iron, and are used for fettling puddle furnaces. (5150.) 



(5) Silicate ore, average sample as prepared for preliminary treatment. Contains 

 4 per cent, of copper. (5149.) 



(6) Silicate ore, after preliminary treatment. The raw ore is dried, and then charges 

 of 15,000 pounds are heated to redness in a close muiile with a small amount of pul- 

 verized coal. By this operation the oxide of copper of the silicate is reduced to the 

 metallic state. The charge is withdrawn from the nuiftlc and cooled with free access of 

 air, by which the copper is again oxidized and thus prepared for solution. (5151.) 



(7) Residues, after treating the prepared silicate ore with a hot solution of proto- 

 chloride of iron and salt ; .still retains 0.r,0 per cent, of copper. (5146.) 



Filial products. 



(1) Cement copper, crystallized metallic copper; separated from the solution by 

 passing over wrought scrap iron. Average siimple. (5147.) 



(2) Cement copper, finely cry.stallized. (30i>31.) 



