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Full text of "Metallurgy Of Cast Iron"

CHAPTER XXIII.                    j
The   past advancement  in  utilizing chemistry  in
making mixtures of cast iron has, among other changes in founding-, resulted in causing many firms to make castings of various types from coke irons, whereas for years past it has been thought that charcoal was the only brand permissible to be used. It is no reason because malleable iron founders and some car wheel and chill roll makers have discovered that coke and anthracite iron can be made to answer their purpose that charcoal iron is .sure to pass into oblivion. A peculiarity between " Bessemer " and " Foundry'* iron lies in the fact that one cannot be told from the other in yards, single pigs or piles, in judging them by fracture. This cannot be held to be true of charcoal vs. coke iron. If there were two yards of pig metal, one being charcoal and the other being all coke or anthracite iron, any one at all familiar with siich irons can generally tell the class of iron each yard contains. We may occasionally see single pieces or piles of coke or anthracite pig iron which will resemble charcoal so closely as to make it difficult to decide its true brand, but, in a general way, charcoal iron is distinguishable from coke or anthracite to prevent the mixture from producing too hard a " grade," as defined in the last paragraph, page 158. For further notes on Bessemer, see pages 146 and 215.ten scrap, and thus often assist in cheapening a mixture. Silicon does not, as a general thing, go as high in Bessemer as in Foundry. When silicon exceeds 2.50 per cent, in Bessemer, it is generally called an " off Bessemer," the same as when it exceeds . 10 in phosphorus. To be over 2.50, the limit for silicon in regular Bes-flexible that anyne castings. analysis which may be given is simply an average of the whole, generally taken from the two ends andith the uncertainty of furnace workings when in urgent need of ten hundred             jon of iron; and Sir........................    2,720     "