"Fred," said Norah, "do tell me what becomes of that melted iron at the bottom of the blast furnace.""There is a hole in the side of the furnace," said Fred. "The men keep it plugged up close and strong with fire-clay. Every twelve hours they come with long iron rods, and break away this clay plug. Then of course out comes the red-hot liquid iron.
"The floor all round the furnace is laid thick withsand, and channels about four inches wide are made in the sand. As the red-hot liquid metal flows out through the hole in the furnace wall it runs intothese moulds of sand. When it gets cold it forms solid blocks of iron. The blocks are called pigs of iron. The iron itself is known as pig-iron. It is also called cast-iron, because it is cast or poured in the liquid state into the sand moulds, and left to cool.""And is this pig-iron fit now to make all sorts ofthings?"" asked Norah.