COLLECTIONS IN ECONOMIC GEOLOGY AND METALLURGY. 53 



Per cent. 



Zinc (Zn) uot present 



Antimony (Sb) trace 



Nickel (Ni) trace 



Cobalt (Co) trace 



Insoluble residue 0. 15 



Silver ( Ag) • 0. 015 or 4. 8 ounces per ton. 



(4) Speiss, an occasional product formed when smelting ores containing arsenic ; it 

 settles to the bottom of tlie slag pot below the matte, being much heavier. It is 

 essentially an arsenide of iron, and is roasted in the stalls and then returned to the 

 blastfurnace. (50927.) Composition: 



Per cent. 



Iron(Fe) 59.42 



Arsenic (As) 31. 17 



Copper(Cu) 5.06 



Lead (Pb) 0.67 



Sulphur (S) 2.«0 



Nickel (Ni) . ^ trace 



Cobalt (Co) trace 



Antimony (Sb) trace 



Silver (Ag) 0. 014 or 4. 2 ounces per ton. 



Insoluble residue trace 



(5) Matte and speiss, a compound piece, showing the separation of the two in the 

 slag pot. (51047.) 



The fine material that is carried forward by the blast is illustrated 

 by a single sample : 



(1) Flue dust, consisting of fine particles of the charge carried off by the blast and 

 collected in the dust chambers attached to the shaft furnaces. It is mixed with 

 quicklime andsiliceous sulphureted Ores and treated in the fusion furnace, after which 

 it goes to the shaft furnaces. (51078.) The following is a typical analysis: 



Per cent. 



Oxide of lead (PbO) 37.65 



Oxide of zinc (ZnO) 5.32 



Sesquioxide of iron (FojOs) 24.98 



ISesquioxide of manganese (MujOs) 1.51 



Alumina (AI2O3) 1.31 



Lime (CaO) 5.26 



Magnesia (MgO) none 



Copper (Cu) trace 



Silica (SiO.j) 8.63 



Sulphuric anhydride (SO3) 1.61?^,,, ,, ., .^ 



Sulphur (8) 2 53 5 Total sulphur, .5.18. 



Carbonic acid (CO2) i 



Water (H2O) > 11. 20 (loss on ignition). 



Carbonaceous matter ) 



Silver (Ag) 0.04 or 11.7 ounces per ton 



To represent the wall accretions which gather on the sides of the 

 furnaces, and which are first sorted and then returned to the shaft fur- 

 naces, four specimens are shown. 



(1) Red oxide of lead (minium), formed in the mortar joints in the crucible of the 

 shaft furnaces. (51041.) 



(2) Furnace accretion, formed on the walls of the shaft furnace when .•smelting ores 



