Author Description

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 edition. Excerpt: ...The following remarks upon some points already described may aid in roughly estimating the quality of cast iron. When the colour is uniform dark grey, the iron is tough, providing there is also high metallic lustre. If there be no metallic lustre the iron will be easily crumbled. The weakest sort of cast iron is where the fracture is of dark colour, mottled, and without lustre. The iron may be accounted hard, tenacious, and stiff when the colour of the fracture is lightest grey, with a high metallic lustre. When the colour is light grey, without metallic lustre, the iron is hard and brittle. When the colour is dull white, the iron is still more hard and brittle than in the last case. When the fracture is grevishwhite, interspersed with small radiating crystals, the iron is of the extreme degree of hardness and brittleness. When cast iron is dissolved in muriate of lime or muriate of mag nesia, the specific gravity is reduced to 2.155. Most of the iron is removed, and the remainder consists of graphite with the impurities of cast iron. The soft grey iron yields to the file after the outer crust has been removed. The quality of the iron in a melted state is really judged by the practised eye from the nature of the agitated aspect of its surface. The mass of fluid seems to undergo a circulation within itself, having the appearance of ever-varying network. When this network is minutely subdivided, it indicates soft iron. If, on the other hand, crystals be thrown up in convolutions, the quality of the metal must be hard. One of the most important points in the welding of cast iron is not to go over the weld twice, as each time any part is melted more than once, the graphite burns out and leaves white iron, which is hard and brittle. One must...