TREATMENT OF THE COMSTOCK OEES. 205 



their coin value, in dollars and cents, are stamped upon them. The value of 

 the ounce of bullion ready for market usually varies between $1 75 and $2 ; 

 the gold representing about one-third and the silver about two-thirds of the 

 whole amount. 



The pulp, after passing from the settlers, in which, as before described, 

 the quicksilver and amalgam are separated from it, is variously treated in 

 different mills. Frequently the whole mass is allowed to pass through agi- 

 tators, tubs or vats of various devices, for the purpose of saving some of 

 the quicksilver and amalgam that is unavoidably carried off with it from the 

 settler. In some mills various kinds of concentrators are employed for a 

 similar purpose, and to obtain the heavy undecomposed sulphurets in concen- 

 trated form; in other cases, where there is water sufficient and the lay of the 

 land favorable, blanket-tables are constructed outside the mill, over which the 

 stream of taihngs^ is allowed to run, and a portion of their valuable contents 

 caught in blankets; and, at convenient points, dams are constructed for the 

 accumulation of tailings, which, after months of exposure to the influences of 

 the weather, may be again worked over with profit. 



The ordinary working result obtained by treating the ore as above 

 described in the pan and settler varies between sixty-five and seventy-five 

 per cent, of the assay value, which, by subsequent treatment, as just indicated 

 in the foregoing paragraph, is increased sometimes to eighty-five or ninety per 

 cent., or possibly a little more. This subject, as well as the costs of working 

 and many other interesting details connected with the business, will be con- 

 sidered more minutely further on, after having first described, in detail, some 

 of the various kinds of crushing and grinding machinery employed in the 

 process, of which the main features have just been given. 



^ The term. " tailings" is applied to the residue of sand or pulp that leaves the sep- 

 arator or agitator after the principal j)ortion of its valuable contents has been extracted. 

 The term "slimes" generally applies to that portion of the ore which is crushed under 

 the stamps to an impalpably fine condition, and whicli usually passes out of the mill 

 without being deposited in the tanks, where the coarser sands are collected for pan 

 treatment. The difference in the value, mechanical condition, and methods of treatment 

 of "tailings" and " slimes" makes the distinction between them an important one. 

 That pa,rt of the " tailings " which, by grinding in the pan, has been reduced to a slimy 

 condition, is sometimes called " pan slimes," and thus distinguished from " battery 

 slimes." 



