152 



DRESSING OF ORES 



754 



charged with tho ore, which is deposited at a less or greater distance, as also pure 

 water for tho purpose of washing the deposited ore, afterwards carried off by moans 



of this operation. 



At tho upper end of these sweeping 

 tables, tho matters for washing are agi- 

 JLBI tated in a chest, by a small wheel with 



vanes, or flap-boards. The launder of 

 the muddy waters opens above a little 

 table or shelf; the launder of pure 

 water, which adjoins the preceding, 

 opens bolow it. At tho lower part 

 of each of these tables, there is a trans- 

 verse slit, covered by a small flap with 

 hinges, opening outwardly, by falling 

 back towards tho foot of the table. The water spreading over the table, may at 

 pleasure bo lot into this slit, by raising a bit of leather which is nailed to the table, so 

 as to cover the small flap when it is in the shut position ; but when this is opened, 

 the piece of leather then hangs down into it. Otherwise the water may be allowed 

 to pass freely above the leather when the flap is closed. The same thing may be done 

 with a similar opening placed above the launder. By means of these two slits, two 

 distinct qualities of slime may be obtained, which are deposited into two distinct 

 canals. The refuse of the operation is turned into another launder, and after- 

 wards into ulterior reservoirs, whence it is lifted out to undergo a new washing. 



Brunton's Machine. This apparatus is adapted for the concentration of ore con- 

 tained in very fine slimes. 



The small water-wheel, shown in fig. 755, is sufficient to drive six of those 



machines, viz. three on each side. Before tho stuff is permitted to enter upon the 

 rotating cloth, it is disintegrated, and passed through a sizing trommel ; it thon 

 flows over the head or dispersing board L, on to tho cloth. This cloth rotates 

 towards the stream on two axles, 11 and M, and is supported by a third roller N. It 

 is also stiffened in its width by numerous laths of wocd. Clean water is introduced 

 behind tho entrance of the slime, in order to give it tho proper consistency. Different 

 degrees of inclination are given to the cloth by raising or lowering tho roller M, by means 

 of the screw K. Tho heavier particles lodged on the cloth are caught in the waggon R, 

 whilst the light matter is floated over the roller M. 



One revolution of the cloth is made in 4 minutes ; its length is about 29.1 fot, so 

 that the speed is 6 feet per minute. The width of the cloth is 4 foot 2 inches. 



Before the slime comes upon the cloth, it is reduced to a size of jth of an inch, and 

 yields an average of 1^ per cent, of copper ; but by means of this machine tho stuff is 

 concentrated so as to afford 5 per cent. In ten hours it will clean 1 ton. Tho speed 

 of the cloth must, however, bo varied with tho condition of tho stuff; if it IT vi-ry 

 poor, tho cloth must travel very much slower, since tho enrichment requires a longer 

 period of time. 



At the end of tho machine, and worked by tho same water- wheel, is a dolly tub : 

 but the dimensions and mode of working this apparatus are fully stated at page 154. 



Bradford 's Slime Apparatus, fig. 756, is intended to imitate that of tho vanning 

 shovel. Tho slimo enters by tho launder A, about 5 inches wide, and descends on 

 tho inclined head A', which expands from the width of tho launder to within a few 

 inches of the width of tho table frame B. The slimo box A" is perforated at D with 

 numerous holes, each of which is fitted with small regulating pins. 



The table B B is 2 feet 2 inches wide, and 2 feet 10 inches long, with bottom formed 

 of sheet copper. It is suspended by tho vertical rods K, K, and varying degrees of 



