Il8 METALLURGY OF CAST IRON.
The evils to be expected from metal possessing much "kish" are mainly in " cold shuts," spongy, porous spots in castings, or the separation of the grains of the metal at places where '4 kish '' is confined. One might as well try to make a union of oil and water as of kish and cast ironi Were it possible to collect or skim off all the " kish " created on top of direct metal, little damage might be expected; but this is not practical, as the " kish " keeps rising to the surface as long as the metal is in a fairly fluid condition. Appliances have been invented with a view to collect the * ' kish '' in pouring runners, etc., before the metal would enter the moulds, but these have proven of little value. It may be said that metal possessing much c<kish" is unfit for pouring castings.
Direct metal free of "kish" can make very good castings, and for some classes of work might often prove more desirable than cupola iron, as less sulphur can be obtained in direct metal than with iron re-rnelted. Iron cannot be re-melted in the cupola, with coke or coal, without increasing its sulphur from .02 to .06 points. The re-melting of pig metal entirely destroys the '' kish '' that appears in direct metal.
The life and fluidity of direct metal, compared to cupola iron, are qualities some will question. If a furnace is working properly, its product will compare very favorably, as regards these qualities, with cupola iron. The author has seen hotter iron from a furnace than is generally obtained from cupolas that hold its life or fluidity exceptionally long. In fact, the author is of the opinion that direct metal can have such an initial heat imparted to it as to create a much greaterourtesy of Mr. Edgar S. Cook, president of the Warwick Iron Co. of Pottstown, Pa. is often surprising how rapidly, as about 75 per cent of the heat generated from the solid fuel is utilized. This is attained where one ton of coke will produce one ton of iron; and Sir........................ 2,720 "