in a white heat, just as the sugar, milk and butter melt together and boil when you make candy.
When a furnace is ready to be drawn as hole at the bottom is opened. Out pours a bubbling, copper-colored river of fire, into a deep ditch of dry sand. Of all the things that were put into the furnace the iron is the heaviest, so the liquid iron falls lowest in the stream, letting the melted rock and ashes rise to the top. Twenty feet or more from the furnace the ditch is dammed. A hole at the base of the dam lets the iron through into a smaller sand canal. The lighter slag flows away on top into slag cars and is carried to dumps.
The iron runs in a golden stream to a great bed of sand under a shed roof. The bed is pitted with holes a couple of feet long and as deep as a man’s arm is thick. These pits, or pockets in the sand, are in regular rows. The iron runs down channels into the pockets. Soon the whole bed is a glowing garden. The pools turn to a sulphur yellow, then to gray and silver as they cool. When they are cold they are clubs of iron. They are raked from the sand and stacked in the yards like cord wood. Those clubs are iron "pigs," or pig iron, and are ready to go to market.
Pig iron is bought by factories to turn into rails, bridge and building iron, machines, engines, locomotives, rods, wire and nails, sheet iron, iron plates for war vessels, guns and cannon, farm machinery and tools, knives, and the thousand and one things of iron and steel that the world uses, from carpet tacks to war ships. Pig iron is simply raw material for making many kinds of iron and steel. You know your mother can make ever so many things out of white flour, by mixing different things with it and cooking them in various ways. So pig iron is melted again and made into cast, or wrought or galvanized iron, and many grades of steel, from bridge and rail steel to the finely tempered kinds used in watch springs and razors. It can be cast in molds, rolled into rails and sheets, drawn into rods and wire, and hammered on forges. Some iron works make only locomotives, some sewing machines, some knives and razors, some sheet iron, or wire, or nails, or plows, or stoves. So foundries and mills need a great many of those little iron pigs.
One of the most interesting kinds of iron manufacturing is the making of steel rails in the rolling mills. In Pittsburg and Chicago rolling mills are owned by the same companies that melt the iron out of the ore in the blast furnaces. As soon as the iron pigs are cold they are loaded on cars and sent over a railroad track in the
