2. The stirring buddle, or chest for freeing the schlamms or slimy stuff from clay, is analogous to the German chests, and consists of two parts; namely, 1. a trough which receives a stream of water through a plug hole, which is tempered at pleasure, to admit a greater or less current; 2. a settling tank with a horizontal bottom. The metallic slime being first floated in the water of the trough, then flows out and is deposited in the tank; the purest parts falling first near the beginning of the run.
3. The nicking buddle is analogous to the tables called dormantes or jumelles by the French miners. See [Metallurgy]. They have at their upper end a cross canal or spout, equal in length to the breadth of the table, with a plug hole in its middle for admitting the water. Alongside of this channel there is a slightly inclined plank, called nicking board, corresponding to the head of the twin table, and there is a nearly level plane below. The operation consists in spreading a thin layer of the slime upon the nicking board, and in running over its surface a slender sheet of water, which in its progress is subdivided into rills, which gradually carry off the muddy matters, and strew them over the lower flat surface of the tank, in the order of their density.
4. The dolly tub or rinsing bucket, [fig. 630.], has an upright shaft, which bears the vane or dolly A B, turned by the winch handle. This apparatus serves to bring into a state of suspension in water, the fine ore, already nearly pure; the separation of the metallic particles from the earthy ones by repose, being promoted by the sides of the tub being struck frequently during the subsidence.
5. Slime pits.—In the several operations of cleansing ores from mud, in grinding, and washing, where a stream of water is used, it is impossible to prevent some of the finely attenuated portions of the galena called sludge, floating in the water, from being carried off with it. Slime pits or labyrinths, called buddle holes in Derbyshire, are employed to collect that matter, by receiving the water to settle, at a little distance from the place of agitation.
These basins or reservoirs are about 20 feet in diameter, and from 24 to 40 inches deep. Here the suspended ore is deposited, and nothing but clear water is allowed to escape.
The workmen employed in the mechanical preparation of the ores, are paid, in Cumberland, by the piece, and not by day’s wages. A certain quantity of crude ore is delivered to them, and their work is valued by the bing, a measure containing 14 cwt. of ore ready for smelting. The price varies according to the richness of the ore. Certain qualities are washed at the rate of two and sixpence, or three shillings the bing; while others are worth at least ten shillings. The richness of the ore varies from 2 to 20 bings of galena per shift of ore; the shift corresponding to 8 waggons load.
1. The cleansing and sorting of the ores are well performed in Cumberland. These operations seem however to be inferior to the cleansing on the grid steps, grilles à gradin, of Saxony (see [Metallurgy]), an apparatus which in cleaning the ores, has the advantage of grouping them in lots of different qualities and dimensions.
2. The breaking or bruising by means of the crushing machine, is much more expeditious than the Derbyshire process by buckers; for the machine introduces not only great economy into the breaking operation, but it likewise diminishes considerably the loss of galena; for stamped ores may be often subjected to the action of the cylinders without waste, while a portion of them would have been lost with the water that runs from the stamp mill. The use of these rollers may therefore be considered as one of the happiest innovations hitherto made in the mechanical preparation of ores.