52 BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



Per cent. 



Magnesia (MgO) *r^^® 



Oxide of lead (PbO) '^-^'^ 



Copper (Cu) trace 



Sulphur (S) 2-^^ 



By 2>^'oducts. 



Five samples of the intermediate products, matte and speiss, are 

 shown. 



(1) Matte, whicli is formed duriug the smeltiug operation and settles to the bottom 

 of the slag pot when drawing off slag. Consisting of A^arious sulphides, especially 

 iron. (51048. ) A typical analysis is as follows : 



Per cent. 



Iron (Fe) 52.27 (varies from 48.00 to 56.00) 



Lead (Pb) 10.72 (varies from 4.5 to 15.00) 



Zinc (Zn) 4.27 



Sulphur(S) -- 24.015 



Copper (Cn) 0.61 



Arsenic (As) 0.56 



Antimony (Sb) uoue 



Lime (CaO) 0.41 (presence accidental) 



Magnesia (MgO) 0A7 (presence accidental) 



Oxygen (O) not determined. 



Silver (Ag) ^-^^^ or 24.5 ounces per ton 



(varies from 21 to 45 

 ounces per ton). 



(2) Matte, after roasting in stalls, whereby the sulphides are changed for the most 

 part into oxides. It is a valuable flux on account of the oxide of iron which it con- 

 tains. (51044.) A typical analysis is as follows: 



Per cent. 



Sesquioxide of iron (Fe,O:0 80. 39 ( Iron (Fe), 56. 27) 



Sesquioxide of manganese (MnaO:,) 0. 93 



Oxide of lead (PbO) 7.91 (Lead (Pb), 7. 34) 



Oxide of zinc (ZnO) 0.98 



Oxide of copper (CuO) •^■22 



Arsenous acid (As,03) 0.86 (Arsenic (As), 0. 648) 



Antimony (Sb) trace 



Sulphur'(S) 1-01 



Silica(SiO:) •^- 21 



Lime(CaO) 3-22 (presence accidental) 



Silver (A<^) 0.0614 or 17.9 ounces per ton. 



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

 settles to the bottom of the 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. (51049.) Composition: 



Per cent. 



Iron(Fe) 58.32 



Arsenic (As) 30.005 



Copper(Cu) 2.09 



Sulphur (S) 4.105 



Lead (Pb) 1-^' 



Manfranese (Mn) not present. 



