732 CtEOLOGY and mining INDUSTPtY OF LEADVILLE. 



(3) The elemeuts of tlic blast: Oxygen, uitrogeu, moisture, and carbonic acid. 



(4) The elements of the fuel: In coke, carbon, moistnre. a little sulphide of iron, 

 and a considerable quantity of ash, formed of silica, alumina, lime, and oxide of iron; 

 in charcoal, carbon, moisture, and a little ash, composed of alumina and alkaline 

 carbonates. 



(5) The elements of dolomites: Carbonic acid, lime, magnesia, with small quanti- 

 ties of iron and other substances. 



(6) The elemeuts of hematite: Peroxide of iron, protoxide of iron, carbonate of 

 iron, with small quantities of other substances. 



(7) The elements of the ores: Carbonate of lead, sulphide of lead, sulphate of 

 lead, pyrite, oxides of iron and manganese, chlorophosphate of lead, chloro-bromo- 

 iodide of silver, gold, zinc, titanic and molybdic acids, and arsenic and antimonic 

 acids, with small quantities of cobalt, nickel, and other substances. 



The examination of the furnace products, which has already been made, affords 

 means of pointing out with precision what becomes of the elemeuts introduced in the 

 furnace. The analyses of slag, bullion, speiss, dust, aud mattes are fair representa- 

 tives of the complete or normal reactions of the furnace, and those of hearth and 

 shaft accretions, of incomplete or accidental reactions. But before entering into these 

 considerations it is necessary to pass in review the principal reactions of lead, silver, 

 and iron compounds, and to study their action upon each other aud upon the chief 

 ingredients either used in smelting or pi^oduced by smelting. At the same time stress 

 will be laid upon the reactions that are represented by specimens found iu the furnaces 

 of Leadville and kept for reference iu the collections of the Geological Survey, and 

 also upon the reactions which were revealed by aualj-.sis. 



REACTIONS CiF LEAD OOMrOUXDS. 



No. I. Reactions of carbonate of lead — Carbonate of lead loses its carbouic acid 

 lietween 170° C. and 200° C. (J. A. Phillips),' and is converted into protoxide of lead. 



No. 2. Reactions of protoxide of lead — Oxide of lead combines iu the dry way with 

 stannic acid, arsenious and arsenic acids, autimouious and antimonic acids, and with 

 peroxide of iron and oxide of zinc (Berthier )^ These reactions take place in the 

 furnaces as is shown by analyses XLIII aud XLIY of peculiar accretions. 



No. 3 Oxide of lead is partially reduced to the metallic state by magnetic oxide 



of iron with formation of peroxide of iron: 3Fe304-f 2PbO=Fe3 04+3Fe203+PbO+Pb 

 (Berthier). The fact that some .slags (see analyses of slags) contain peroxide of iron 

 in the state of silicate seems to indicate that this reaction takes place. 



No. 4. — Oxide of lead in excess is reduced to the metallic state by sulphur with 

 formation of sulphurous acid: 2PbO-f S=2Pb+S0.,(Berthicr). This reaction undoubt- 

 edly occurs when the charges contain pyrites. 



No. 5. — Oxide of lead is reduced by ar.senic with formation of lead aud ar.senite 

 of lead: iPbO + As=PbO, AsO:,+3Pb (Berthier). 



No. 6. — Conversely, metallic lead reduces arseuite of lead with formation of basic 

 arsenite of lead and arseniuret of lead: 2(PbO,AsU3)-|-4Pb=3PbO, AsOj+PbAs 



■ Liihij; uud Kopp's .Talivesb., IS.'il, p. 357. 



-All tlic (iitot.itioiis frimi Bertbier are taken fnmi lii.s Tiaiti- lies es.^ais pnr la voie seclie, Paris, 

 IrtlM, and may also l>o loiiiul in Peroy"s Metallurgy of Lead, Loudon, 1870. 



