The Manufacture of Iron, in All Its Various Branches (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1850 edition. Excerpt: ... degree, upon a clear understanding of the qualities of the metal, and of the modes of working it. b. The form of the basin of the hearth, the height of the tuyere, and the pressure and the quantity of the blast, cannot be fixed by any general rule, and depend on coal, metal, and the workmen. We shall endeavor to explain the leading principles in each case; but their application is to be varied according to local circumstances. c. The quality of the charcoal determines, to a certain extent, the dimensions of the hearth, the dip of the tuyere, and the pressure of the blast, as well as the amount of metal to be smelted by. one heat. Soft coal, from pine wood and poplar, requires a larger and deeper fire, a greater dip of the tuyere, and weaker blast, than charcoal from hickory and maple. Soft coal works more slowly than hard coal. Dirty or sandy coal, which has been received from the coalings in wet weather, or which has been exposed to sand or mud in the yard, should be refused altogether, or at least carefully dried and cleaned; because each pound of sand removes three or four pounds of iron, for no conceivable purpose whatever. Coal that is not larger than an egg, will answer tolerably well for a blomary fire; but strong and heavy coal is far more serviceable. In the preparation of coal for the blomary and the blast furnace, we are guided by different rules; that is to say, the small coal from the coalings is taken to the former, and the large coal to the latter. It should always be remembered that coal which contains sand and dirt is far more injurious in the forge than in the blast furnace. d. So great are the practical difficulties in this kind of work, that fluxes are employed to a very limited extent. Hammer-slag is sometimes used as a...