. The pictorial sketch-book of Pennsylvania, or, Its scenery, internal improvements, resources, and agriculture, populary described . In the engraving on page 118, a is the shaft hearth, where ore and fuelare thrown in ; & 6 are the grate-bars, which can be removed to let downthe roasted ore; c e are side arches, which permit access to the draftholes; d d d d avQ four arches, including the work arch. To startoperations in such an oven, the grate bars are covered with wood;upon this is placed cither charcoal or coal; then a layer of coal andore alternately, until the oven is filled, after which
. The pictorial sketch-book of Pennsylvania, or, Its scenery, internal improvements, resources, and agriculture, populary described . In the engraving on page 118, a is the shaft hearth, where ore and fuelare thrown in ; & 6 are the grate-bars, which can be removed to let downthe roasted ore; c e are side arches, which permit access to the draftholes; d d d d avQ four arches, including the work arch. To startoperations in such an oven, the grate bars are covered with wood;upon this is placed cither charcoal or coal; then a layer of coal andore alternately, until the oven is filled, after which the fire is the lower strata of ore are sufiiciently roasted, they are takenout at the grate bars. The air-holes, d d d d are designed to admitair when necessary, as well as to observe the progress of the the top of the ore sinks, it is replaced by fresh layers. This kindof furnace is used only for the hydrates, carburets, and other easilyworked ores, but will not answer for carbonates, sulphurets, or evenmagnetic ores—for they are too soon smelted. They are generallyroasted in heaps in the open COAT^ BARROW. Putting a furnace into blast is a very delicate and responsibletask—requiring great prudence, watchfulness, and activity. Tosupply the furnace with fuel, a barrow, similar to the above, is em-ployed. A new furnace requires firing for two or three weeks beforethe rermlar charges of ore can be thrown in. After the stack andhearth-stone are sufficiently dry, the charges of ore are introduced insmall quantities, and are afterwards gradually increased. The furnace is always exposed, at the outlet, to the liability of chil-ling ; that is, the iron clinkers in the interior, and suddenly coolsnear the mouth or top-hole, impairing the di-aft, and not unfrequentlyentirely choking it up. in whicli case the whole interior work has 120 LOCOMOTIVE SKETCHES. sometimes to be taken out and rebuilt. Under these circumstances,introduction of the charges of ore
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Keywords: ., bookcentury1800, bookdecade, booksubjectminesandmineralresources
