614 MESriNG INDUSTRY. 



or mining district must remain within narrow limits so long as its operations 

 are restricted to the treatment of first-class ores exclusively. 



Within the past year this subject has received much attention in this 

 district, and two establishments have lately been erected for the purpose of 

 concentrating ores of low or moderate value. 



One of these, known as the Georgetown Dressing Works, was built and 

 is owned by the Wilson and Cass Company, partly for the purpose of work- 

 ing low-grade ores produced by the mines of the company and partly with 

 the view of purchasing similar ores from the mines of the neighborhood, 

 dressing them so as to separate the valuable mineral from the gangue and 

 shipping the concentrated product to the smelting works of the East. This 

 mill, not quite finished when visited by the writer, is situated a mile or more 

 below Georgetown, near the stream, from which an abundant power is 

 obtained. The process consists of wet-crushing, separating the coarser pro- 

 duct on jigging machines of various kinds, and concentrating the fine material 

 on Rittinger tables and other slime-dressing appliances. There are five bat- 

 teries of stamps, containing five heads each. Each stamp weighs 450 

 pounds and falls 10 inches 60 times per minute. The screens are made of 

 brass wire and are of different sizes. The first three batteries, through 

 which all the ore must pass, are provided with coarse screens, containing 

 eight square meshes per lineal inch. From these batteries a large portion of 

 the ore escapes in a coarse condition. The crushed material passes thence 

 on to several jigging machines, which, though differing in some details, are, 

 in many respects, like those of Mr. John CoUom, that will be described 

 further on. They consist of boxes or tanks that are furnished with sieves of 

 any desired degree of fineness. The ore is carried by the stream of water 

 upon the sieves, and, being kept in agitation by water, the action of which 

 may be understood by referring to the description of Mr. Collom's machine, 

 the heavy ore settles upon the sieve, the finer portion passing through into 

 the box below, while the light, earthy portion of the material or pieces of 

 gangue, still carrying particles of ore, is washed off from the sieve into a 

 sluice or trough in front. By means of this first separation a portion of the 

 clean rich ore, both coarse and fine, is obtained, while the gangue, requiring 

 further treatment, is raised by a simple elevator and delivered to another 



