COLLECTIONS IN ECONOMIC GEOLOGY AND METALLURGY. 49 



Per cent. 



Oxide of zinc (ZuO) 5.01 



Lime(CaO)...-'. 12. 3;{ 



Silica (SiOj) 28.75 



Arsenic (As) not present 



Copper (Cu ) not present 



Antimony (Sb) trace 



Sniphur (S) trace only 



Silver ( Ag) '3 ounces per ton 0. 01 



Fuel. 



(1) Coke, El Moro, Las Animas County, Colorado. (.51332.) 



Per cent 



Water (H2O) 0.28 



Fixed carbon, by diiference 83.77 



Ash 15.95 



100. 00 

 Composition of ash : 



Silica (SiOi) 10. 6G 



Sesquioxide of iron (Fe^O:?) 1. 03 



Alumina (AI.2O3) 3.85 



Lime(CaO) , 0.15 



Undetermined 0. 26 



(2) Piiion pine charcoal. (51333.) 



Products. 



(1) Base bullion or argentiferous lead. Contains the lead and silver of the ma- 

 terials charged into the furnaces, and also the small amount of gold. The amount 

 of gold and silver varies, though the silver has never exceeded 350 ounces per ton 

 and the gold 1.5 ounces per ton. Owing to the exceptional purity of the Madonna 

 ores, which enter largely into the shaft furnace charge, the bullion is very free from 

 impurities and is very easy to refine. It is shipped from the works in car loads of 

 300 bars, weighing 98 pounds each. (51080.) 



(2) Base bullion. Cores of metal taken from the bar, one from the top and one 

 fBom the bottom of each, in order to determine its value by assay. (51089.) 



(3) Base bullion, assay sample ; consisting of the cores represented by No. 51089, 

 taken from each bar of the shipment. These cores are melted down and cast into a 

 bar, and samples are cnt from each end and the middle, which are assayed to deter- 

 mine the value of the shipment. (51081.) 



The slags resulting- from the smelting operation, change frequently 

 with changes in the ore charge, but the limit of the changes within 

 which the furnaces will work clean and successfully is quite small, when, 

 however, the furnace is not working properly abnormal slags of very 

 varying composition are formed. The principal constituents of clean 

 slags are silica, protoxide of iron and lime, and to these in certain cases 

 may be added oxide of zinc. The varying proportions of these ele- 

 ments constitute the difference in the slags. The following are exam- 

 ples of clean slags : 



(1) (51082): Showing square prismatic crystals of the following composition : 



Per cent. 



Silica (SiO.2) 30.605 



Protoxide of iron (FeO) * 23. 70 



Protoxide of manganese (MnO) I. 51 



* Iron (Fe) 18.56. 

 9110— No. 42 4 



