BOOK IX. 



407 



third smelter, as I have said, adds to the tertiary cakes when he re-smelts 

 them, while from the " final " cakes, thrice roasted and re-smelted, is made 

 black copper**. 



The riidis copper from which pure copper is made, if it contains little 

 silver or if it does not easily melt, is first smelted in the third furnace of which 

 the tap-hole is always open ; and from this are made cakes, which after 

 being seven times roasted are re-smelted, and from these copper is melted 

 out ; the cakes of copper are carried to a furnace of another kind, in which 

 they are melted for the third time, in order that in the copper " bottoms " 

 there may be more silver, while in the " tops " there may be less, which 

 process is explained in Book XI. 



♦*The method of this paragraph involves two main objectives — first, the gradual 

 enrichment of matte to blister copper ; and, second, the creation of large cakes of copper- 

 lead-silver alloy of suitable size and ratio of metals for liquation. This latter process is 

 described in detail in Book XI. The following groupings show the circuit of the various 

 products, the " lbs." being Roman librae : — 



Charge, 

 /Crude ore 



Lead slags . . 

 J Schist 

 JFIux 



Concentrates from 

 \ slags & accretions 



5,400 lbs. 

 3 cartloads 

 I cartload 

 20 lbs. 



Small quantity 



/Primary matte (i) 1,800 lbs. 



Hearth-lead & litharge 1,200 „ 



Lead ore 

 j Rich hard cakes (A .,) 

 1 Liquated cakes 



Slags (B) 



Concentrates from 

 V accretions 



300 

 500 

 200 



Products. 

 Primary matte (i) . . 600 lbs. 



Silver-copper alloy (A) 50 ,, 



Slags (B) 



Secondary matte (2) 1,800 lbs. 



Silver-copper-lead 

 alloy (liquation 

 cakes) (A 4 . . 1,200 „ 



Slags (B 2) 



3rd 



4th 



/Secondary matte {2) 1,800 lbs. 



Hearth-lead & litharge 1,200 ,, 



Lead ore . . . . 300 ,, 



i Rich hard cakes (A 4) 500 ,, 



Slags (B2) 



Concentrates from 

 \ accretions 



(Tertiary matte (3) . . 



Poor hard cakes (A 5) 

 j Slags (B3) 



Concentrates from 

 > accretions 



II cartloads 

 3 



Tertiary matte (3) 1,300 lbs. 



Silver-copper-lead 



alloy (liquation 



cakes) (A3) . . 1,100 ,, 



Slags (B 3) 



Quaternary hard cakes 



matte (4) . . . . 2,000 lbs. 



Rich hard cakes of 



matte (A 4) . . 1,500 ,, 



5 th 



[Roasted quartz 



J Matte (4) (three times 



( roasted) 



II cartloads 



Poor hard cakes of 



matte (A 5) . . 1,500 lbs. 



Final cakes of matte (5) 



Final matte three times roasted is smelted to blister copper. 

 The following would be a rough approximation of the value of the various products : 



(l.) Primary matte 



(2.) Secondary matte . . 



(3.) Tertiary matte 



(4.) Quaternary matte 



A. Copper-silver alloy 



A2 Copper-silver-lead alloy 

 A3 



A4 Rich hard cakes 



A5 Poor hard cakes 

 Final blister copper 



= 158 ounces troy per short ton. 



85 ., 



60 „ 



Indeterminate. 



388 ounces Troy per short ton. 

 145 ,. 

 109 „ „ „ 



97 ., 

 Indeterminate. 

 12 ozs. Troy per short ton. 



