Slag-hearth.
（Metallurgy.) A furnace for treating slags run from the surface of lead in a smeltingfurnace. The shaft is a parallelopipedon 26 × 22 inches at the base, and 3 feet high. The sole-plate a is of cast-iron, and slopes down to the receiving-basin or fore-hearth b; cast-iron beams, called bearers, c c, on each side of the sole-plate, support the side walls of sandstone, and also the cast-iron plate d, called the fore-stone, forming the front of the shaft. The back is of cast-iron up to the tuyere-hole, above which it is of sandstone. In front of the fore-hearth b is a cistern e, through which water flows, so that slags which flow over the fore-hearth may be shattered, and the lead contained in them be readily washed out. The lead itself flows over the fore-hearth into an iron pot f, which is kept hot over a fire. The metal obtained in this way is less pure than that extracted directly from the ore.
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| Slag-hearth. |
