434 MINING mOUSTEY. 



arranged for wet-crushing. Some mills have a part of their stamps adapted 

 to dry and a part to wet-crushing, so that either method may be selected 

 according to the character of the ore to be worked. 



The ore, after being crushed, either dry or wet, is then worked in pans. 

 These are of the kind already described. Among those in use are Varney's, 

 Wheeler's, Hepburn's, McCone's, and Fountain's. The method of operation, 

 the duration of the grinding and amalgamating process, the "chemicals" used, 

 are generally the same as in the mills about the Com stock. Concerning the use 

 of chemical reagents it may be said that some mill-men use a much larger per- 

 centage of salt than is employed in working the Comstock ores, amounting, in 

 some cases, to 2 per cent., or 40 pounds per ton of ore. The necessity for this 

 is not apparent in working ore in which the silver is already supposed to exist 

 in the form of chloride ; and it would seem that the use of salt in such propor- 

 tions is more the result of habit than careful reasoning. The practice appears 

 to have been introduced into the district by men who were accustomed 

 to the working of so-called "rebellious" ores, or those that require to 

 be roasted with a large percentage of salt, as is the case at Austin ; and who, 

 though dispensing with the roasting process, retained the use of salt, appa- 

 rently without much consideration of the necessity of the case. Other mill- 

 men coming from the vicinity of Virginia City adopted the methods in use 

 there, employing two or three pounds of salt and a little sulphate of copper 

 with each charge of ore. According to Captain Eawlings, superintendent of 

 the Manhattan mill, near Hamilton, an increase in the amount of salt used 

 with the ore did not improve the result. 



The percentage of the assay value obtained from the ore is shown in the 

 statement of the Consolidated Company's operations. It varies from 70 to 

 little over 80 per cent. In some mills the percentage obtained is said to 

 be still higher, even exceeding 90 per cent., especially where dry-crushing 

 is employed, as in this case there is less mechanical loss by the action of the 

 water and in the slimes. At the Manhattan mill several assays of tailings, 

 made in the month of August, 1869, gave an average value of about $13 per 

 ton. An assay of the slimes at the same time gave a value of $64 per ton. 



The bullion produced is generally very fine. The precious metal is sil- 



