TREATMENT OF THE COMSTOCK OEES. 271 



Humboldt County. This furnace consists of a shaft something over 20 feet 

 high and from 3 to 4 feet square. At the base of the shaft, on two opposite 

 sides, are fire-places from each of which a short flue leads to the main shaft. 

 At the top of the shaft is the feeding machinery, which supplies the finely 

 pulverized ore in a continuous stream. Just below the top of the shaft is a 

 flue through which the gases escape, and leading from the furnace to a series of 

 dust chambers, in which the heated current may deposit that portion of the fine 

 material which it carried upward with it. An auxiliary fireplace in this flue 

 serves to sustain the heat and prolong the oxidizing and chloridizing operation. 

 A discharge door is at the bottom of the main shaft, whence the bulk of the 

 material that has been acted upon is withdrawn ; and similar doors are 

 placed at convenient points along the main flue and in the dust chambers. The 

 main stack, for the final escape of the gases, is at the end of the dust cham- 

 bers and is about 40 feet high. 



In the regular operation of the furnace the ore is mixed with salt 

 on the drying floor and then crushed under stamps. The screens used in the 

 crushing battery are No. 40. It is then raised by an elevator to the top of the 

 furnace and deposited in the hopper of the feeding machine, whence it is sup- 

 plied continuously to the furnace. The heat in the shaft is maintained as 

 uniformly as possible, and at a sufficiently high degree to keep the ore, which 

 accumulates at the bottom, red hot. From time to time this ore is discharged 

 through the doors at the base of the shaft and in the flue, or canal, leading to 

 the dust chamber. 



It is claimed by Mr. Stetefeldt, as a result of actual experience at Reno, 

 that this furnace performs a more efficient chloridizing roasting, with far less 

 cost for labor, fuel, and salt than is the case with the reverberatory furnaces. It 

 is said that about ninety per cent, of the silver contained in the ore is chlo- 

 ridized. One Stetefeldt furnace, operated by 8 men, accomplishes the treat- 

 ment of 20 tons of ore, which would require 10 reverberatory furnaces and the 

 labor of 36 men. The fuel thus far used in the furnace at Reno averages 

 about two cords per day, and may roast at that rate of consumption the same 

 quantity of ore which would require the consumption of ten cords in a rever- 

 batory furnace. The salt used in the Stetefeldt furnace varies from three to 

 six per cent., according to the richness of the ore, while in the reverbera- 



