254 MrND^G INDUSTEY. 



ores, whicli require to be roasted with salt, chloridizing the silver and prepar- 

 ing it for amalgamation. This roasting process, however, has hitherto been 

 too expensive to be used profitably in working slimes. Owing to these diffi- 

 culties the slimes produced in crushing have not been, at least until lately, a 

 source of much profit. In some mills, as has been already stated, it has been 

 the custom to mix a part of the slimes with the sand of the tanks, or, in 

 other cases, with common tailings, and so work them over in pans ; but the 

 data are not sufficient to furnish any reliable estimate of the degree of effi- 

 ciency attained in extracting their valuable contents. In other mills the 

 stream bearing the slimes has been allowed to run ofi" with the common tail- 

 ings, finding its way to the grand reservoirs at the mouths of the canons, 

 while others have accumulated them in dams, made specially for that purpose, 

 holding them in reserve for a time when they might be turned to some 

 account. 



Within a year or two past much progress has been made in working 

 these slimes in pans without previous roasting, and several mills of consider- 

 able capacity have been devoted exclusively to this business, purchasing their 

 supply of slimes from neighboring crushing mills, and treating them in such 

 manner as to obtain a fair percentage of their value with considerable profit. 



The Messrs. Janin and Mr. Ira S. Parke have mills of this description, 

 in Six-Mile Canon, not far below the large mill of the Gould and Curry 

 company. 



The methud of treatment employed in working slimes in these mills 

 does not difier much, in mechanical details, from that by which the fresh ores 

 are worked, the most notable feature of the process being the use of much 

 larger quantities of chemical reagents than is customary in milling ordinary 

 ore. The reagents themselves do not difier in kind, but the quantity is 

 increased to an extent which makes it possible to believe in their efficient 

 action. 



In the Janin mill there are four McCone pans. These each receive 

 2,500 pounds of slime at each charge.^ 



1 The charge of ore for this pan is 4,000 or 5,000 pounds, but as slimes increase 

 greatly in bulk on the addition of water, it wUl not take more than 2,500 pounds of the 

 dry material. 



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