y 



566 MINING INDUSTET. 



The price paid by the Smelting Company for these huddled (not blan- 

 keted) taihngs varies from $13 to $45 in currency, the average, perhaps, 

 being about $20 per ton. 



In order to form an approximate estimate of the total percentage of the 

 gold that is extracted by the stamp mill, we may assume, from the data al- 

 ready stated in the foregoing pages, that 55 per cent, of the whole is obtained 

 by the first crushing and amalgamation in the batteries and on the tables, 

 leaving 45 per cent, in the tailings. Assuming, further, that the average 

 value of the gold in these tailings is $11 per ton, and that six tons, containing 

 %^Q^ are concentrated into one ton, the yield of which, taking a general aver- 

 age of the product derived from working those that are blanketed, and from 

 the sale of those that are huddled, may be placed at $22, it follows that one- 

 third of the value of the raw tailings, or 15 per cent, of the original gold value 

 of the ore, is extracted by processes subsequent to the first crushing and 

 amalgamation; which, being added to the 55 per cent, previously obtained, 

 gives a total of 70 per cent, for the whole course of treatment. 



It should be observed that when tailings are sold to the Smelting Works 

 and there treated by the method to be described presently, instead of being 

 worked in pans, as they frequently are in mills, the actual value extracted 

 from them is considerably greater than that on which the above calculation 

 is based. 



The mills and milling methods of the gold-producing regions of Colo- 

 rado are doubtless capable of many improvements, but it seems clear that in 

 the present state of metallurgical science, the local condition of the country, 

 the costs of labor, materials, &c., the stamp mill affords better means of 

 working the low-grade ores than are offered by any other method yet at- 

 tempted. Compared with all others it possesses the advantage of cheap- 

 ness — a requisite condition in treating ores of such low average value, and, 

 even in this particular, important improvements may be, and gradually are, 

 being made. 



One great desideratum, in order to improve the efficiency of the process, 

 and, at the same time, to reduce the cost of working, in some respects, appears 

 to be the adoption of some suitable method of concentration, which, being 

 combined with the present process of crushing and amalgamation, should ren- 



