620 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



bers of eight smelters. The following figures, obtained by analysis of this mixture, 

 may be taken to represent the relative proportions of chlorine, bromine, ami iodine in 

 the silver ores : 



Chloride of silver 89. 10, equivalent to chlorine e^-i. 45 



Bromide of silver 10. 45, equivalent to bromine IC. 83 



Iodide of silver 0.45, equivalent to iodine 0. 7-i 



100. 000 100. 000 



Special stress has been laid upon the composition of the chloride ores, for the 

 reason that they play an important part in lead smelting in Leadville. To chlorine, 

 bromine, and iodine is due a great part of the loss in lead, not only because chloro- 

 bromoiodide of lead is a very volatile compound, but also because chloro-bromoiodo- 

 phosphates and sulphurets of lead are found which are also remarkable for their great 

 volatility. 



Average of ores — Mr. Th. Fluegger, assayer of the Harrison Reduction Works, in 

 Leadville, has published in the Engineering an<l Mining Journal of March, 1880, an 

 analysis of a sample from 1,000 tons, representing specimens from every producing 

 mine in Leadville. This analysis, made with probably insufiflcient means in the lab- 

 oratory of one of the smelters, has evidently no pretension to scientific accuracy, since 

 some of the elements — sulphur, arsenic, antimony — are left uncombined and since 

 all the rare elements are not indicated. It is given here, however, because upon it 

 have been based the main features of the chemical discussion of the blast furnace. 



If it is assumed that the quantity of silver reported in this analysis is correct, it 

 represents an average quantity of silver of nearly 90.5 ouuces to the ton. This figure 

 appears exaggerated, for the reason that the proportion of silver to lead is one ounce 

 to five pounds, while in practice mixtures aimed at contain one ounce of silver to six 

 pounds of lead. But the average percentages of lead (23), iron (18), and silica (22.5) 

 agree precisely with the general composition of the smelting charges in Leadville. 



Analysis VI. — Average ore. 



Carbonic acid 5. 58 



Oxide of lead 24.77 



Silica 22.59 



Sulphur 0.90 



Protoxide of iron 0. 89 



Peroxide of iron 24.86 



Protoxide of manganese 4.03 



Silver 0.31 



Lime 2.36 



Magnesia 3. 04 



Arsenic ,. o. 01 



Antimony 0.02 



Potash and soda 0. 98 



Chlorine 0.09 



Water ,^. 53 



Alumina 3.99 



Gold, copper, zinc Trace 



99. 95 



Silver, 90.5 ounces to the ton ; lead, 23 per cent. ; iron, 18 per cent. ; silica, 22.59 

 per cent. 



