SAMPLING AND CRUSHING. 629 



laid in a thin layer on the floor, and quartered down very carefully until small enough 

 to be dried easily. The amount of moisture is determined by desiccation of this 

 sample, previously weighed. When dry it is passed through Cornish rolls set to one- 

 eighth of an inch or through small mills. It is once more well mixed and quartered down 

 until small enough to be ground on the buck-plate or in the mortar, and passed 

 through fine sieves, about 70 meshes to the linear inch. This done, the sample is once 

 more well mixed and divided into three parts, one of which is assayed by the smelter, 

 the other at the mine, and the third by an independent assayer, or more generally kept 

 in reserve for reference in case of dispute. Sometimes the bulk of the sample ob- 

 tained from every tenth shovelful from the wagon is reduced by setting apart every 

 fifth shovelful. This reduced sample is afterwards subjected to the treatment which 

 has just been described in detail. 



Sampling works Every smelter in Leadville possesses a sampling floor, with 

 ore-beds, crushers, and ore-bins; but there are besides three large sampling works. , 

 which are independent of the smelters and where the buying, assaying, crushing, 

 drying, sampling, and selling of ore only are carried on. These works belong to Messrs. 

 A. E. Meyer & Co., Eddy &. James, and Gillespie & Ballon. 



The sampling works are provided with a large number of bins for the preparation 

 and classification of ores of every grade and from every mine; and, as at the smelters, 

 the machinery, crushers, Cornish rolls, and mills are driven by steam-power. Large 

 open spaces are kept for the accumulation of ore-dumps and the preparation of ore- 

 beds of a given composition. These arc made by spreading layer upon layer of ores 

 of known weight and contents in silver and lead. Drying is carried on on a large 

 scale, the driers consisting of large parallelopipedic cuts in the ground, about six feet 

 wide and twenty feet long, provided with a coal fire-place at one end, connected with, 

 a sheet-iron stack at the other, and covered over on a level with the ore floor with 

 sheet-iron, upon which the ore to be dried is spread in layers. 



The advantages offered by these works are twofold. The prospectors and small 

 miners can always dispose of their small lots of ore, and the large ones of those ores 

 which are in any way exceptional or out of the usual run. On the other hand, the 

 smelters can always find their supplies of ores- of a given composition ready for the 

 furnace, or special ores to modify or complete the composition of their own ore beds 

 or mixtures. 



CRUSHING. 



Sand ores do not require crushing; in fact, they are already in dust or pieces 

 too small for the furnace, and require mixing in convenient proportion with crushed 

 ore in order to be fit for use. But hard ore and sand ore in lumps require crushing, 

 as well as the limestone, iron-stone, and old slags which are nsed as fluxes. This is 

 effected, both at smelters and at sampling works, by means of compact but powerful 

 stonebreakers or crushers, always driven by steam-power. 



Machines used. The crushers mostly used in Leadville are Blake crushers manu- 

 factured by the Blake Crusher Company, New Haven, Conn., and by the Farrel 

 Foundry and Machine Company, Ausonia, Conn. At the sampling works one or two- 

 Alden crushers manufactured by E. T. Copeland, New York, are also in use. 



