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 46 . 



The rudis 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, hi order that in the copper " bottoms " 

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

 process is explained in Book XI. 



46 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 " Ibs." being Roman librae : 



CHARGE. 



Crude ore . . . . 5,400 Ibs. 

 Lead slags . . 3 cartloads 

 . Schist . . . . i cartload 



I Flux . . . . 20 Ibs. 



Concentrates 



ist 



2nd 



3rd 



4th 



5th 



6th 



from 

 \ slags & accretions 



Primary matte (i) 

 Hearth-lead & litharge 

 Lead ore 



Rich hard cakes (A ^) 

 Liquated cakes 

 Slags (B) 



Concentrates from 

 accretions 



Secondary matte (2) 

 Hearth-lead & litharge 

 Lead ore 



Rich hard cakes (A 4 ) 

 Slags (B a ) 

 Concentrates from 

 j accretions 



/Tertiary matte (3) .. 



Poor hard cakes (A 5 ) 

 -(Slags (B 3 ) 



Concentrates from 

 ' accretions 



[Roasted quartz 



I Matte (4) (three times 



( roasted) 



Final 

 The 

 (i.) 



(2.) 

 (3-) 



(4.) 



A. 



A 2 



A 3 



A 4 



A 5 



Small quantity 



i, 800 Ibs. 

 1,200 ,, 



300 



500 



200 



PRODUCTS. 

 Primary matte (i) . . 600 Ibs. 



Silver-copper alloy (A) 

 Slags (B) 



Secondary matte (2) 1,800 Ibs. 



i, 800 Ibs. 



1,200 



300 



500 ,, 



ii cartloads 



Silver-copper-lead 

 alloy (liquation 

 cakes) (A 2 ) 



Slags (B a) 



Tertiary matte (3) 

 Silver-copper-lead 

 alloy (liquation 

 cakes) (A 3 ) 

 Slags (B 3 ) 



1,200 



1,300 Ibs. 



1,100 



ii cartloads 



Quaternary hard cakes 



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



Rich hard cakes of 



matte (A 4 ) . . 1,500 , 



Poor hard cakes of 



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



Final cakes of matte (5) 



matte three times roasted is smelted to blister copper. 



following would be a rough approximation of the value of the various products ; 



Primary matte 

 Secondary matte . . 

 Tertiary matte 



Quaternary matte 

 spper-silver alloy 

 Copper-silver-lead alloy 



f> 



Rich hard cakes 

 Poor hard cakes 

 Final blister copper 



158 ounces troy per short ton. 



85 > ., 



60 



Indeterminate. 



388 ounces Troy per short ton. 

 145 

 J 9 



97 



Indeterminate. 

 12 ozs. Troy per short ton. 



