746 GEOLOGY AND MIXING INDUSTRY CF LEADVILLE. 



4. That the camp is provided with the necessary plant to work profitably such 

 by-products as are generally rich in silver and either completely neglected, or treated 

 imperfectly and with a considerable loss of silver. 



5. That the mode adopted at a great many smelters of mixing and resmeltiug 

 with caustic lime the chamber dust, formed in considerable quantity, is the best that 

 could have been devised, and that it would be advisable to substitute pure lime for 

 the dolomitic lime used in Leadville for this operation. 



6. That the numerous imperfections noticeable at various smelters are mostly 

 intentional and based on economical grounds, and not on ignorance, for smelting is 

 conducted in Leadville by very clever superintendents and smelters. 



7. That the smelting of lead ores in the presence of iron-stone has here been 

 brought to a state of great practical perfection, and is carried on most successfully 

 from one year's end to the other with the greatest regularity at a dozen smelters, and 

 that superintendents of smelters do not hesitate to introduce in the charges sometimes 

 very large quantities of galena, which are reduced with the greatest facility. 



8. That, owing to the peculiar nature of the Leadville ores and to the great alti 

 tude at which smelting is performed, which increases the volatility of lead compounds, 

 attempts ought to be made to substitute caustic lime free from magnesia for the raw 

 dolomite used in Leadville, in order to avoid as much as possible the formation of 

 volatile lead compounds. 



9. That, caeteris paribus, dolomite forms as good a flux as calcitic limestone, so far 

 as the actual working of the blast-furnaces is concerned, and that the fluidity of the 

 slag thus formed is not only irreproachable but quite remarkable. 



10. That, besides the substances existing in large quantities in the camp, such 

 as silica, sulphur, carbonic acid, lime, magnesia, alumina, oxides of iron and man- 

 ganese, lead, silver, chlorine, and phosphoric acid, the following substances exist in 

 small quantities: Sulphuric acid, titanic acid, bromine, iodine, zinc, baryta, gold, 

 nickel, molybdenum, arsenic, antimony, and copper; and that traces of the following 

 substances may be detected: Tin, bismuth, cobalt, indium, selenium, tellurium, cad- 

 mium, and a new metal, which has been imperfectly studied as yet, and which appears 

 to be intermediate between the metals of the iron group and those of the lead group. 



11. That the ores of Leadville are either rich in lead and poor in silver, rich in 

 silver and poor in lead, or equally rich in both silver and lead, and very variable in 

 composition ; but that, by judicious admixtures of various ores, ore-beds of sensibly 

 the same composition are made at the smelters, which are needed to insure regularity 

 in the smelting operations. 



12. That the quantity of lead completely lost in the atmosphere is sensibly twice 

 as large as the quantity of lead caught in the dust-chambers generally used. 



13. That the crude bullion extracted in the blast-furnaces of Leadville by the 

 process referred to in section 7 is of very fair quality, and that a little of its silver and 

 some of its lead exist there in the state of sulphides. 



14. That mattes (both iron and lead mattes), which had hitherto been considered 

 as entirely formed of sulphides, are crystallographic compounds of sulphides of iron 

 and lead and crystallized magnetic oxide of iron. (This last observation, however, in- 

 terferes in no way with the fact that in various smelting operations mattes entirely 

 formed of sulphides are produced.) 



