MATERIALS USED IN SMELTING. 641 



CONSTRUCTION MATERIALS. 



Common brick The bricks used iu the construction of outer walls aud dust- 

 chambers are made from clays found in California and Big Evans gulches. Tbey are 

 made in a very simple way: Into a wooden mold (Figs. 9 and 10, Plate XL1V), divided 

 into three compartments having the shape and dimensions of bricks, a lump of the 

 clay, brought to the proper degree of consistency, is jammed at one blow without sub- 

 sequent effort or pressure. The excess of clay, represented by c iu Fig. 9, is cut off by 

 means of an iron wire, both ends of which are fixed to a wooden handle (Fig. 11, Plate 

 XLIV). The mold is then reversed and gently shaken. The detached bricks are 

 dried as usual iu long rows iu the air. They are then piled up in large stacks and 

 burned. 



Fire-brick The fire-bricks used for the lining of furnaces are sent to Leadville 

 chiefly from the manufactory of Messrs. Evans & Howard, St. Louis, Missouri, and 

 also from the Cambria Fire-brick Company, Golden, Colo., and from the Denver Fire- 

 clay Company, Denver, Colo. 



Tapping clay Good plastic and refractory clay is needed for tyinp stones, tap- 

 holes, tamping, and steep (brasque) used in the lining of furnace crucibles. The fol- 

 lowing analysis of tapping clay found in Big Evans gulch aud used at the Grant 

 smelter was made by Dr. M. W. lies, of the Grant Smelting Works: 



ANALYSIS VII. TAPPING CLAY. 



Silicate of a linn in a 74.5 



Water 14.0 



Oxide of irou 3.0 



Magnesia Trace 



Carbonate of lime 6. 8 



Free silica... 1.0 



99.3 

 (M. W.Iles.) 



Other materials When the smelting works are erected on the plans of super- 

 intendents, the smelting implements are derived from various sources. The cast- 

 ings, however, such as water-jackets, iron pillars, plates for supports and frames 

 of crucibles, ingot-molds, slag-pots, etc., are generally made by Messrs. Heudey & 

 Meyer, of Denver; while the boilers and engines are made by different foundries. Iu 

 many cases smelters have found it more convenient and advantageous to obtain the 

 whole of their smelting plant from Messrs. Fraser & Chalmers, of Chicago, 111., who 

 are prepared to furnish a complete smelting outfit, from the crushers aud furnace 

 down to ingot-molds and tainpiug-rods. 



FUELS AND FLUXES. 



Coke Coke is made in El Moro, on the Rio Grande Railroad, from Cretaceous 

 coals found there; it is known in Leadville as El Moro coke. It is also made iu Como, 

 on the South Park Railroad, from Como Cretaceous coals, and is then known in Lead- 

 MON xn 41 



