REACTIOXS IN BLAST FUENACES. 733 



(Bertbier). Tbe presence of arsenite of lead iu all the oxide of lead couipouuds of the 

 furnace and the presence of arsenic iu bullion show that reactions 5 and G are of fre- 

 quent occurrence. 



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

 same way as with arsenic (Bertbier). Tbe presence of autimonious acid in oxide of 

 lead coni[)ounds and of antimony in bullion shows that these reactions are constantly 

 taking place iu tbe furuace. 



Nc. 8 — Protoxide of lead is reduced to the metallic state by iron with formation 

 of magnetic oxide of iron: J:PbO + Fe3=Fe304+l'b (Bertbier). To this reaction is 

 undoubtedly due jiart of the magnetic oxide of iron found iu slags and other furnace 

 ])roducts. 



No. g. Protoxide of lead and silica combine easily at tbe temperature at which 

 the oxide of lead becomes pasty. The silicate 3PbO,Si'J2 is very fusible and very 

 fluid. Tlie silicate 2PbO, SiOj is pasty (Percy-Becli).^ Tbe presence of silicate of lead 

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



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

 evolved and lead is reduced to the metallic state (Bertbier, Percy-Smith): I'bS+ 

 2PbO=3Pb+S02. This is one of the fundamental rea(;tious of blast-furnaces which 

 has been pr.jved too often to need demonstration. 



No. II — Oxide of lead is completely reduced to the metallic state by cbai'coal, 

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

 water (Bertbier, Percy, and others). 



No. 12 — Oxide of lead is reduced by zinc to tbe metallic state by ibrmation of 

 oxide of zinc: PbO+Zn=Pb + ZijO (Bertbier). The oxide of zinc deposited in accre- 

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

 agglomeration. 



No. 13. Reactions of silicate of lead — Silicate of lead behaves almost exactly lilce 

 protoxide of lead in its reaction.s upon sulphur, iron scales, iron, carl)on, 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 tbe furuace at tlie zones of agglomeration ; but reactions jSTo. 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 (Bertbier, 

 Percy). 



No. i5. — Suli)hate of lead is reduced by lead to the state of oxide with evolution 

 of sulphurous ac.d: PbO, S03+Pb=2PbU+SlJ., (Bertbier, 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: Pb0,S03+ 4Fe=Fe304+FeS+Pb. 

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

 this reduction. 



'The i|Uo:utii>us IVdih Percy aiul liii. assistauts, whose uames follow Percy's, are talicu from 

 Percy's Metalhirf^y of Lead, Loiidou, 1870. 



