REACTIONS IX BLAST FURNACES. 733 



(Berthier). The preseuce of arsenite of lead iii all the oxide of lead compounds of the 

 lu mace and the preseuce of arsenic in bullion show that reactions 5 and C are of fre- 

 quent occurrence. 



No. 7. Aiitimouy acts on oxide of lead, and lead on oxide of antimony, in the 

 same way as with arsenic (Berthier). The presence of antituouious acid in oxide of 

 lead compounds and of antimony in bullion shows that these reactions are constantly 

 taking place in the furnace. 



No. 8 Protoxide of lead is reduced to the metallic state by iron with formation 

 of magnetic oxide of iron: 4PbO-f Fe 3 =Fe 3 O 4 -|-Pb (Berthier). To this reaction is 

 undoubtedly due part of the magnetic oxide of iron found in slags and other furnace 

 products. 



No. 9. Protoxide of lead and silica combine easily at the temperature at which 

 the oxide of lead becomes pasty. The silicate 3PbO,Si0 2 is very fusible and very 

 fluid. The silicate 2PbO, SiO 2 is pasty (Percy-Beck). 1 The presence of silicate of lead 

 in all the slags shows that this substance is formed in the furnace. 



No. 10. Oxide of lead and galena. In this well-known reaction sulphurous acid is 

 evolved and lead is reduced to the metallic state (Berthier, Percy-Smith): PbS+ 

 i>PbO=3Pb+SO 2 . This is one of the fundamental reactions of blast-furnaces which 

 has been proved too often to need demonstration. 



No. ii Oxide of lead is completely reduced to the metallic state by charcoal, 

 coke, oxide of carbon, hydrogen with formation of carbonic oxide, carbonic acid and 

 water (Berthier, Percy, and others). 



No. 12 Oxide of lead is reduced by zinc to the metallic state by formation of 

 oxide of zinc: PbO+Zu=Pb+ZnO (Berthier). The oxide of zinc deposited in accre- 

 tions and fumes is undoubtedly produced in this way by zinc reduced in the zone of 

 agglomeration. 



No. 13. Reactions of silicate of lead Silicate of lead behaves almost exactly like 

 protoxide of lead in its reactions upon sulphur, iron scales, iron, carbon, carbonic oxide, 

 galena, etc. (Percy-Beck). 



NO. 14 Silicate of lead is completely reduced to the metallic state by mixtures 

 of oxide of iron and carbon (Percy-Beck). This is undoubtedly one of the chief reac- 

 tions of the furnace at the zones of agglomeration ; but reactions No. 13 take place in 

 most of the zones of the furnace. 



No. 15. Reactions of sulphate of lead Sulphate of lead is decomposed by silica with 

 evolution of sulphurous acid and oxygen and formation of silicate of lead (Berthier, 

 Percy). 



No. 16. Sulphate of lead is reduced by lead to the state of oxide with evolution 

 of sulphurous ac.d: PbO, SO 3 +Pb=2PbO+SO 2 (Berthier, Percy-Smith). 



No. 17 Sulphate of lead is reduced by iron to the metallic state with formation 

 of magnetic oxide of iron and sulphide of iron: PbO,SO 3 + 4Fe=Fe 3 O 4 +FeS + Pb. 

 There is but little doubt that the mattes of Leadville owe their origin in great part to 

 this reduction. 



1 The quo.atious from Percy and hi.% assistants, whose iiauies follow Percy's, are taken from 

 Percy's Metallurgy of Lead, London, 1870. 



