. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. ary, laveries a gradins. Thesemethods of freeing the ores from the pulverulent earthy matters, consist in placing them,at their out-put from the mine, upon gratings, and bringing over them a stream of water,which merely takes down through the bars the small fragments, but carries ofl the pulver-ulent portions. The latter are received in cisterns, where they are allowed to rest Ionsenough to settle to the bottom. The washing by steps is an extension of the precedingplan. To form an i
. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. ary, laveries a gradins. Thesemethods of freeing the ores from the pulverulent earthy matters, consist in placing them,at their out-put from the mine, upon gratings, and bringing over them a stream of water,which merely takes down through the bars the small fragments, but carries ofl the pulver-ulent portions. The latter are received in cisterns, where they are allowed to rest Ionsenough to settle to the bottom. The washing by steps is an extension of the precedingplan. To form an idea, let us imagine a series of grates placed successively at differentlevels, so that the water, arriving on the highest, where the ore for washing lies, carriesoff a portion of it, through this first grate upon a second closer in its bars, thence to athird, &c., and finally into labyrinths or cisterns of deposition. The grilles anglaises are similar to the sleeping tables used at Idria. The system of theseen gradins is represented in fig. 671. There are 5 such systems in the works at Idria, for671 pjf. the sorting of the small morsels of quicksilver ore, intended for the stamping mill. Thesefragments are but moderately rich in metal, and are picked up at random, of various sizes,from that of the fist to a grain of dust. These ores are placed in the chest a, below the level of which 7 grates are distributed,so that the fragments which pass through the first b, proceed by an inclined conduit on tothe second grate c, and so in succession. (See the conduits 1, o, p). In front, and on alevel with each of the grates b, c, d, &c., a child is stationed on one of the floors, 1, 2 3,to 7. A current of water, which falls into the chest a, carries the fragments of ore upon thegrates. The pieces which remain upon the two grates 6 and c, ai-e thrown on the adjoin-ing table I, where they undergo a sorting by hand; there the pieces are classified, 1. intogangue to be thi-own away ; 2. into o
Size: 3035px × 823px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1840, booksubje, booksubjecttechnology
