264 MEsriNG mDUSTRT. 



SECTION V. 



TEEATMENT OF EIEST-OLASS ORE. 



The treatment of the first-class ores was briefly referred to in the first 

 part of this chapter. The combinations in which the gold and silver exist in 

 these unfit them for profitable treatment in the simple grinding and amalga- 

 mating process which has been described in the foregoing pages. They 

 require a chloridizing roasting, after which they are amalgamated in barrels. 

 The quantity of high-grade ore now produced in the district is so small that 

 the single establishment of Mr. J. H. Dall, in Washoe Valley, has much more 

 than sufficient capacity for its treatment. 



It has already been shown that during the twelve months ending July 

 1, 1868, the Savage mine, which was then the chief source of high-grade ore, 

 produced but 277^ tons of so-called first-class ore; and in the following year 

 only 68| tons. The establishment referred to, which is built in connection 

 with a wet-crushing and pan-amalgamating mill, has twenty stamps for dry 

 crushing, eight reverberatory roasting furnaces, and twelve barrels, capable of 

 treating some three or four hundred tons per month. 



The method of treatment to which the ore is subjected consists of dry- 

 ing, crushing by stamps without the use of water, roasting with salt, amalga- 

 mation in revolving barrels, and the separation of the gold and silver from the 

 quicksilver by the usual method of retorting. These principal features of the 

 process will be briefly described. 



Deying. — The drying kiln consists of a series of flues, covered by a cast- 

 iron floor, on which the ore, already reduced to a size suitable for stamping, 

 is spread. The surface for the reception of the ore is about 8 feet wide by 

 12 feet long. The iron is cast in sections or plates, 8 feet long by 3 feet 

 wide, with a strengthening rib on the under side. The base of the kiln is 

 brickwork, and the flues are about 8 inches deep. They are covered by the 

 iron plates. At one end of the kiln is a fireplace, and at the other a stack, f 



so that the heat passes from one end to the other under the iron cover or 

 floor, on which the ore is spread to a depth of 4 or 5 inches. The ore is 

 constantly raked and turned until quite dry. 



When the kiln is conveniently placed, as in some similar establishments 



