734 .GEOLOGY A1,*D MIXING INDUSTRY OF LEADVILLE. 



No. 18 Sulpbate of lead is reduced by carbon to the state of sulphide: PbO, 

 SO 3 +C 2 =PbS-|-2CO 2 (Gay-Lussac), 1 and also by carbonic oxide (Rodwell). 2 The 

 sulphide of lead of the mattes is produced partly by these reactions. 



No. ig. Sulphate of lead is decomposed by lime with formation of sulphate of 

 lime and oxide of lead; sulphate of lime has been pointed out in the analyses of some 

 furnace products. 



No. 20. Reactions of sulphide of lead. Sulphide of lead is somewhat volatile; it is 

 sublimated at high temperatures (Berthier, Percy). This sublimated galena in fine 

 distinct irisated crystals is one of the constituents of normal shaft accretions. 



NO. 21 Sulphide and oxide of lead react upon each other with formation of 

 metallic lead and sulphurous acid (see reaction Xo. 10). 



NO. 22 Sulphide of lead and metallic lead combine together and form subsnl- 

 phides and alloys. The analyses of bullion and skimmings prove this reaction. More- 

 over, the metallurgical collection of the Survey conlains specimens of alloys highly 

 charged with sulphide of lead. 



No. 23 Sulphide of lead is reduced by zinc: Pb.S+Zn=Pb+ZnS (Percy-Smith). 

 The sulphide of zinc found in normal accretions and also in lead fumes is certainly 

 deposited in virtue of this reaction. 



NO. 24 Sulphide of lead and sulphate of lead react upon each other with forma- 

 tion of metallic lead and sulphurous acid: PbS+Pb'J,SU 3 =2Pb+2SO 2 (Berthier, 

 Percy). 



No. 25 Sulphide of lead and iron produce one of the most important reactions 

 of the blast furnace; lead is completely reduced to the metallic state and sulphide of 

 iron is formed: PbS+Fe=Pb+FeS (Bertbier). Most of the sulphide of iron in mattes 

 is produced in this way. 



No. 26 Sulphide of lead and oxide of carbon act slightly upon each other with 

 formation of sulphide of carbon (Rodwell). 3 In all probability some of the silica found 

 in that portion of the fumes which escapes in the air is volatilized in the state of sul- 

 phide of silicium by the sulphide of carbon thus produced. 



No. 27. Sulphide of lead mixed with lime :u.d carbon is partly reduced with for- 

 mation of sulphide of calcium and carbonic oxide: HPbS+CaO+C=Pb+PbS,CaS-t- 

 CO (Berthier). This important reaction, which undoubtedly takes place in the zone of 

 agglomeration of the furnace, accounts for the sulphide of calcium in the slags. 



No. 28 Sulphide of lead, heated with oxide of iron and carbon, produces incta! 

 lie lead and sulphide of iron: 4PbS+2Fe 2 O 3 +3C=4Pb+4FeS+3CO 2 ." This reaction 

 is interesting as indicative of what actually takes place in the furnace. 



No. 29. Sulphide of lead and basic silicate of protoxide of iron react upon each 

 other with formation of metallic lead, and iron and lead matte: 2(3FeO, SiO 3 )+5PbS= 

 2(2FeO,SiO 3 )+2(PbS, FeS) + SO 2 +Pb 3 (Percy Cloud). This important reaction is 

 illustrated by the specimens of hearth accretions or slag-mattes in the collection of 

 the Surrey. 



1 Ann. de Chim. et de Phys., 1836, 73, p. 435. 



3 Journal of the Chemical Society, new series, 1863, p. 42. 



3 Journal of the Chem. Soc., antea cit., p. 48. 



4 Jordan, Erdmann's Journal, 1831, 11, p. 334. 



