CHAPTER XVI. BANKING FURNACES AND CUPOLAS. The principle involved in "banking" is simply to do everything possible to prevent air finding access through the body of a furnace to the fuel, so as to stop rapid combustion and sustain the fire only in a dormant state until it is found desirable to again '' blow in '' the furnace. This is similar in principle to the practice of smothering a fire in a stove over night so that next morning little labor or fuel would be required to start a good fire and provide a quick breakfast. The old plan of ''banking" a furnace involves considerable labor and expense. One system followed is to encircle the furnace with a curbing of plates bolted together, or planks stood on end, projecting 2 or 3 feet above the tuyeres, the planks being held together by means of hemp or wire ropes, the space between the furnace and the curbing- being about 2 feet, which is filled up with a close grade of sand. Before encircling the furnace with this curbing, the slag pipe and the tuyeres are all taken out and all their pipe connections removed. (The pipe connections to the coolers are not disturbed, as water is left on them during the time of 4 'banking.") After this the tuyere holes in the brickwork, etc., are filled of silicon and sulphur. In fact, some furnaeemen have so mastered the art of making iron that they can run weeks at a time without varying 30 per cent, in silicon or three points in sulphur, when making iron having less than 1.25 silicon. It is with silicon above 1.50 per cent. also in very hot weather, as shown by Chapter XVII. --that the greatest difficulty is experienced, at present, in regularly obtaining a uniform grade of pig metal.main runner as it flows to the pigs and pouring it into aourtesy of Mr. Edgar S. Cook, president 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 "