Iron is one of the commonest, and so cheapest, of all the metals; and this is a good thing, for it is the most useful. It is very hard and strong, and, with the proper machinery, easily worked. Its chief fault is that it quickly rusts when it is exposed to water or damp air unless it is kept always polished or covered with paint.
Like other metals, iron is found in certain kinds of rocks and has to be got out of the earth by mining. The iron mixed with rock in its natural state is called iron ore. The iron ore is first crushed and then put into very hot furnaces until the iron is melted out of the rock. It then flows out of the furnace as a white-hot liquid, into molds, where it is left to cool. When it is cold it is very hard, but also brittle (that is, easily broken).
In this state, it is called cast-iron or pig-iron
To make this cast-iron strong and tough, it is again melted and stirred about; and after that, when it is red hot, it is rolled under heavy rollers and beaten with great hammers. When the iron so treated is cold, it is not only very hard but also very tough, and cannot be broken easily. This wrought iron is used wherever great strength is wanted, as for building ships, and making bridges, or for girders to support buildings.
Lastly, wrought iron is made into steel, by a special process. Steel is the most perfect form of iron. It is very strong and hard, and yet it can bend without breaking. It takes a bright polish and can be ground down to a very fine point or sharp edge. It is used for all machinery, engines, parts of ships, and for knives, scissors, needles, swords, and scientific instruments.
The word iron is sometimes used to express human qualities. A determined man is said to have a will of iron; iron-hearted means hard and cruel. The Duke of Willington was called Iron Duke because he would never yield. Sardar Patel was called the Iron man of India.