732 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



(3) The elements of the blast: Oxygeu, nitrogen, moisture, and carbonic acid. 



(4) The elements of the fuel: In coke, carbon, moisture, 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. 



(G) The elements of hematite: Peroxide of iroH, 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 irou and manganese, chlorophosphate of lead, chloro-bromo- 

 iodide of silver, gold, zinc, titanic and uiolybdic 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 elements introduced in tlie 

 furnace. The analyses of slag, bullion, speiss, dust, and 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 and upon the chief 

 ingredients either used in smelting or produced by smelting. At the same time stn-ss 

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

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

 also upon the reactions which were revealed by analysis. 



REACTIONS or LKAI) roMI'i>rM.~. 



No. i. Reactions of carbonate of lead Carbonate of lead loses its carbonic acid 

 between 170 C. and 200 C. (J. A. Phillips), 1 and is converted into protoxide of lead. 



No. 2. Reactions of protoxide ofiead Oxide of lead combines in the dry way with 

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

 peroxide of iron and oxide, of zinc (Berthier) 2 These reactions take place in the 

 furnaces as is shown by analyses XLIII and XL1V of peculiar accretions. 



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

 of iron with formation of peroxide of iron : 3Fe 3 O.,+L'Pl>O=Fe 3 O4+3Fe 2 O 3 +PbO + Pb 

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

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



No. 4 Oxide ofiead in excess is reduced to the metallic state by sulphur with 

 formation of sulphurous acid: 2PbO+S=2Pb+SO 2 (Berthier). This reaction undoubt- 

 edly occurs when the charges contain pyrites. 



NO. 5. Oxide of lead is reduced by arsenic with formation of lead and arson! te 

 ofiead: 4PbO+As=PbO, AsO 3 +3Pb (Berthier). 



No. 6 Conversely, metallic lead reduces arsenite ofiead with formation of basic 

 arseliite of lead and arseniuret ofiead: 2(PbO,Asl) 3 )+4Pb=5PbO, AsO 3 +PbAs 



1 Liebig nml Kopp's Jahresb., 1851, p. -357. 



- All the quotations from Berthier are taken from his TraitS (lea essais par la voie seche, Paris, 

 1834, and may also be found in Percy's Metallurgy of Lead, London, 1870. 



