Indian Science and Technology in the Eighteenth Century: Some Contemporary European Accounts c24.8

c24.8

6. For converting cast iron into bar iron, the first process generally employed in England is called ‘refining’, and consists in fusing about a ton of cast iron at once in flat open furnaces about three feet square, where it is exposed to two hours or more to the action of a strong blast, by which it is supposed a portion of the carbon it contains is burnt off. Much gas escapes from the surface of the metal during the operation, and a large quantity of black bubbly slag separates, after which the metal when run out and allowed to cool, has a white silvery appearance, is full of bubbles, is very brittle, and has acquired the property of hardening by being suddenly cooled. In ‘refining’, about four or five hundredweight of coals is used to the ton of cast iron, and the metal loses from twelve to seventeen per cent of its weight.