744 GEOLOGY AND MI^"ING IXDUSTEY OF LEADVILLE. 



Zo«e of aij<jlomeration 1.095° C. 



"Weight of charge entering 2one 397, 0*293 



It loses : 



One-eleventh t.f the total loss in dnst andfnmes 0.5293 



One-third of the CO2 from carhonates 5 8020 



(Of this I is reduced in upper zones, while g escapes.) 



Oxygen from jV FeO reduced toFe 1.-9249 



(This forms with CO 5.2935 pounds CO2, of which | is reduced above, while 

 . . I escapes. J, 

 C oxidized hy 1 CO2 expelled from carbonates in zone 1,200° C. (0.8289 pounds 



CO2) 0.2261 



C oxidized hy Jj CO2 formed in zone l.i'OO^C. (32.1.256 pounds COj) 8.7016 



17. 2439 



Total C oxidized in zone 1,095=C 8. 9877 



Total CO formed in same zone 41. 9426 



Of this latter there is used for redaction of ore 3.3686 



Leaving for escaping CO 38. 5740 



Zone of combustion and reaction by contact of solid matter, 1,200>^ C. 



"Weight of charge entering zone 379.7854 



It loses; 



One-eleventh of the total loss in dust and fumes 0. 5293 



One-third of the CO2 from carbonates 5.8020 



(Of this f is reduced in upper zones, while f escapes.) 



C oxidizid to CO2 32.1257 



38. 4580 



Remaining in furnace 341.3274ff 



"Weight of bullion reaching zone of crucible 61. 0170 



"Weight of .slag produced 281.6520 



343. 2090 



Cheinical reactions of the different zones Soiue iinpoitaut reaCtiOUS begin tO take 



place ill zone 570° C. and are continued in zone (i'o° 0. Oxide of lead acts ou galena, 

 •sulphide of silver, and pyrites, and some sulphurous acid is evolved. Mattes begin 

 to form. Oxide of lead acts on silica, and some silicate of lead is formed. In pi-actice 

 dolomites lose here a portion of their carbonic acid, but the discussion has been carried 

 on as if dolomite behaved like carbonate of lime, in order to get at extreme results. 



In zone 780° C, the important reaction of reduction of lead taking place, several 

 more reactions are produced in consequence. Metallic lead acts on arseuiate and 

 antimoniate of lead, forming ar.seniuret and antimoniuret of lead, with regeneration 

 of oxide of lead. Metallic lead acts also on suli)hate of lead, with regeneration of oxide 

 and evolution of sulphurous acid; all the reactions which have escaped completion iu 

 the upper zones are completed here. Jletallic lead acts on galena, and subsulphides 

 are formed. Sulphide of lead acts on sulphate and oxide of lead, with evolution of 

 sulphurous acid and reduction of lead. Sulphide of lead acts on silicate of lead, and 

 mattes are produced. Metallic lead acts on chlorobromoiodide of silver and forms 



a The discrepancy between this number and that next below, representing the sum of bullion and slag, is mainly due to 

 the fact that while Mr. Guyard expressly says (p. 739) he has neglected consideration of speiss and matte in this discussion, 

 he nevertheless allows for the redaction of j'g FeO in zone 1,095*^ C. Calculations carried out with a view to correctiug the- 

 abovc discrepancy give 32.7272 as the amount of carbon burnt in zone 1.200^. Such coiTccticn involves, naturally, slight alter- 

 ations in some of the figuies. representing loss in all except the four highest of the other zones, and also alters the data 

 relative to the amount of blast theoretically required. A second causi- of difference between the above numbers is found 

 in the fact that the figures for composition of charge (p. 740) are accurate in some cases only to the second decimal figure. 

 The slight inaccuracies iu the values of the third decimal necessarily involve errors iu calculations carried to four decimal 

 places. (.S.F. E.) 



