MOULDING AND CASTING PIG IRON, ETC. 101 FIG. 24- the sand. But like all else in mechanics, there is a limit to abuse, and too much carelessness in wetting down the floor of a casting house can result in disastrous *'boils." floulding- pig beds is generally done by three men, who will mould up fifteen to twenty beds in about one hour. The main runner leading to' the pile's Xos. r, 2, 3, 4, 5, 6 and 7, Fi^. -2t), i>n^e 1 is rallrd the ** sow runner." There are generally from 24 to 2<H pigs to a sow. lOaeh sow is leveled, likewise the pigs connected to it, but each bed is, in commencing from the lower end, made E^^f^^J^^^^S^^ *Tf FIG. 27.stream of iron is started, the furnace-man cannot plug up a c' run-out'' or dampen the ardor of a little " kick," the same as when pouring a mould, and hence the precaution of not being dependent upon one's judgment to get sand just the right temper,'' etc. Where sand is as open as is generally used for pig beds, and as deep in the floor as above described, water, after having been absorbed to a certain point, will, to a large degree, filter through coarse sand towards the bottom of its depth, so that should an excess of water have been used, the chances are it will not cause the ft' boil'' it would certainly do if the sand was of such a character as that generally used for green sand molding in a foundry. Another point which makes it desirable to use such open-grained sand is that of saving labor in mixing sands. About all the mixing that furnace sand generally gets is what the force of water from a two-inch nozzle gives it. I have seen such a stream play steadily on one spot for two or three minutes and no attention paid to it. If moulding sand in a foundry received such abuse, the iron would mostly go to the roof the moment it struckat the regular notch. It 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 "