. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. esof calcinations, fusions, and roaslings, executed upon the ores and the matters resultingfrom them. The furnaces are of the reverberatory construction; they vary in their dimensions andin the number of their openings, according to the operations for which they were in-tended. There are 5 of them :—1. The calcining furnace or calciner; 2. The meltingfurnace; 3. The roasting furnace or roaster; 4. The refining furnace; 5. The heatingor igniting furnace. 1. The calcining furnace rest
. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. esof calcinations, fusions, and roaslings, executed upon the ores and the matters resultingfrom them. The furnaces are of the reverberatory construction; they vary in their dimensions andin the number of their openings, according to the operations for which they were in-tended. There are 5 of them :—1. The calcining furnace or calciner; 2. The meltingfurnace; 3. The roasting furnace or roaster; 4. The refining furnace; 5. The heatingor igniting furnace. 1. The calcining furnace rests upon a vault, c, into which the ore is raked down afterbeing calcined; it is built of bricks,and bound with iron bars, as shown in the elevation,fig. 296. The hearth, b B,figs. 296 and 298, is placed upon a level with the lower horizon-tal binding bar, and has nearly the form of an ellipse, truncated at the two extremities ofits great axis. It is horizontal, bedded with fire-bricks set on edge, so that it may be re-moved and repaired without dist\irbing the arch upon which it reposes. Holes, not visible. in the figure, are left in the shelves before each door, c c, through which the roasted oreis let fall into the subjacent vault. The dimensions of the hearth b b are immense, beingfrom 17 to 19 feet in length, and from 14 to 16 in breadth. The fire-place, a., fig. 298, isfrom 4^ to 5 feet long, and 3 feet wide. The bridge or low wall, b,fig. 302, which sepa-rates the fire-place from the hearth, is 2 feet thick; and in Mr. Vivians smelting-worksis hollow, as shown in the figure, and communicates at its two ends with the atmosphere,in order to conduct a supply of fresh air to the hearth of the furnace. This judiciouscontrivance will be described in explaining the roasting operation. The arched roof ofthe furnace slopes down from the bridge to the beginning of the chimney, f,figs. 297,298, its height above the hearth being at the first point about 26 inches, and from 8 to 12at
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Keywords: ., bookcentury1800, bookdecade1840, booksubje, booksubjecttechnology
