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MIXTURES FOR WHITE IRON CASTINGS, ETC. 291
and generally of rectangular form, being in size about eight feet high in the center of the arch, by ten feet wide and eighteen feet long. The castings are placed in rectangular pots, which are set upon the bottom and often built four or five high until a furnace is filled. The ovens are heated with natural and pro-ducer gas; also coke and coal. The action is purely one of heating, and the temperature ranges from 1,400 to 1,900 degrees F.
Some firms anneal castings without packing them, placing them in the ovens singly and allowing the heat to come in direct contact with their surfaces. This is generally done only with work that is not particular, as the heat scales the castings badly. Malleable people in general, when an order is very urgent, will often anneal castings outright in the melting furnace. The results, however, are very unreliable and cause the surface to look badly. The effect is generally an incomplete conversion of the combined carbon to the temper carbon. Annealing is like other workings in iron, there are many little things that must be learned by experience before success can be had.ith different firms. One firm may anneal similar thicknesses of castings in half the time another will take. The changes effected by annealing are chiefly in lowering the total carbon in the skin and turning the combined that remains into temper carbon, the silicon, sulphur, manganese, and phosphorus remaining practically the same. The time occupied in annealing ranges from one to seven days, with castings packed in boxes, etc. This wide difference is due to different customs and the character of castings to be treated. The ovens used are of simple construction in small ladles to the moulds, than that coming from furnacesthat would stand the tests of the United States Government for gun carriage work rightfully belongs to Messrs. Robert Poole & Son Co. of Baltimore, Md., and Muirkirk pig iron made by me. This was in 1893. The War Department at first refused to accept cupola iron as gun iron, but when it was fully demonstrateduois Iron Co., Illinois Steel Co., Jefferson Iron Co., Kittan-ning Iron & Steel Co., C. A. Kelly Plow Co., Lebanon Furnace, Longdale Iron Co., Lackawanna Iron & Steel Co., Logan Iron........................ 16,720 " t-