272 MINING INDUSTEY. 



tory furnaces about twice that quantity is expended; the principal cause of 

 difference being that in the shaft-furnace the salt is more thoroughly utilized, 

 every particle accomplishing its purpose. 



It is also claimed by Mr. Stetefeldt that the bullion produced from ore 

 roasted in this furnace is of a higher quality than where the reverberatory is 

 employed, owing to the decomposition of the chlorides of the base metals. 

 These chlorides are formed in the shaft-furnace but are again decomposed in 

 the presence of steam derived from the burning fuel, thus forming hydrochloric 

 acid and the oxides of the metals. The roasted pulp accordingly contains much 

 less of the chloridized base metal than it would if the ore were roasted in a 

 reverberatory. In this respect it is held that the furnace is admirably adapted 

 to the treatment of base ores. 



The cost of roasting per ton, thus far, at Reno, is said by Mr. Stetefeldt 

 to be between $6 and $7, which may be reduced by projected improvements 

 and by working the furnace at full capacity. 



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