126 METALLURGY OF CAST IRON.
is such as to be very apt to make it difficult to get a furnace working well for a week or more after it is ' 'blown in."
Banking is generally done in cases where a shutdown is thought to be only temporary. If a furnace " blows out," which means a clear shut-down, nearly the same amount of fuel and lime is often charged to follow the stock down as if the furnace was being " banked." This is done so as to burden the blast and keep the heat or flame of the furnace from escaping and thus better reduce the stock of ore to metal and also cause less heat to affect the upper lining as well as the bell and hopper from melting, and makes a cleaner furnace when " shoveled out." There are a few that will *' blow out'' a furnace without covering the last charge of ore well with fuel and lime, but this plan is not considered good and safe furnace practice.
In "blowing out" a furnace, the fuel used to follow the stock down can be largely saved, for as soon as the last tap of iron is made, and the blast shut off, the tuyeres P, Fig. 10, page 49, can be all pulled out and the incandescent fuel raked out on to the ground floor, where with a hose, water will soon dampen the fire in the fuel, which will be found to be but little burned, so that it can be used over again. After the fuel is all pulled out level with the tuyere, water can then be thrown by a hose to dampen the fire in the hearth, so that in six to ten hours after the blast is stopped all fire can be extinguished.
Where banking a cupola might'be thought of, as referred to at the close of this paper, it is generally well to have a charge of fuel follow the last charge of iron,out," as the accumulation of ash and dirt from a furnace banked to exceed three months of the Warwick Iron Co. of Pottstown, Pa. is often surprising how rapidly, as about 75 per cent of the heat generated from the solid fuel is utilized. This is attained where one ton of coke will produce one ton of iron; and Sir........................ 2,720 "