98 BULLETIN 12, UNITED STATES NATIONAL MUSEUM. 



(4) Slag, second skiaimiug. (5498L) 



(5) Copper, taken just before poling. (54977.) 

 ((i) Slag, third skiniiuiug. (549o2.) 



(7) Copper, taken from the bath after the skimming during the poling. (54978.) 



(8) Slag, skimmed after poling. (5498:5.) 



(9) Test piece, a small sample taken from the bath and hammered, in order to test 

 its (luality, just before beginning to cast. (5521L) 



Final product. 

 (1) Ingot. (.54979.) 



Accessories. 



(1) Sand, used for making the furnace bottom. (55210.) 



(2) Pole, hickory, used to deoxidize the copper bath. (54984.) 



THE LAKE SUPERIOK NATIVE COPPER WOUKS. 



These works refine the dressed material from the miue works, but the 

 only portion of the operation shown is the smelting in cupola furnaces 

 of the slags produced in refining the native copper in reverberatory 

 furnaces. These slags are charged into a cupola furnace with limestone 

 and anthracite coal and produce a very impure pig copi)er. The furnace 

 usually runs 7 to 8 hours, smelting 10 to 14 tons of slag. 



The usual proportion of the charge is about 120 pounds of slag, 50 

 pounds of limestone, aud 40 pounds of anthracite coal. After each 

 short run the furnace is dumped aud prepared (or the next charge. The 

 collection shows : 



(1) Refuse, consisting of slag, cinder, copper, etc., from previous fusions in the 

 cupola. (.54330.) 



(2) Slag, average sample ; from refining furnaces. (54331.) 



(3) Anthracite coal, used for fuel. (54332.) 



(4) Limestone, used for flux. (,54333.) 



(5) Pig copper, product of the smelting. (54335.) 



(6). Slag, crystallized; taken from the casting box above the copper. (54334.) 



A single run of the furnace was observed by the collectors, E. B. 

 Kirby, e. m., and E. L. Zukoski, e. m. At 5 p. m. a tire of wood and 

 coke was made up in the furnace to dry it out, and about 800 pounds of 

 coke were used. At 7.30 the next morning regular charging commenced, 

 and at 10.45 six tons of slag had been charged. At 1 p. m. this was all 

 smelted and the copper was tapped. This run of the furnace is repre- 

 sented by five samples of slag : 



(1) Taken at 9.25 a. m. (5433C.) 



(2) Taken at 10 a. m. (.54337.) 



(3) Taken at 10.30 a. m. (54338.) 



(4) Taken at 11.30 a. m. (54339.) 



(5) Taken at 12.30 a. m. (54340.) 



THE SMELTING OF COPPER. 



The extraction of copper from its ores may be divided into four pro- 

 cesses. In some cases the metal from a given ore will pass through all 

 these stages, while in others some of the stages will be omitted entirely. 



