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BESSEMER   VS.   FOUNDRY   IRON.                     159
semer, is not so objectionable to steel men as it is for the phosphorus to be over . 10. Steel works will often accept Bessemer over 2.50 in silicon, but seldom accept phosphorus over .10, unless the iron is used to make steel by the " basic process,'' a method by which phosphorus can be greatly eliminated from the iron by reason of qualities in the lining having an affinity for phosphorus. Bessemer iron, to be such, in the regular sense, must not have over one-tenth of one per cent, of phosphorus, which is a small quantity compared with one per cent, often utilized in Foundry iron in order to give the molten metal good life and fluidity.
It is to be understood that in all the mixtures shown on pages 157 and 158 the sulphur is not to exceed .030 or the manganese .5o-in the pig; if it does, then higher silicon will be necessary in proportion to their increase; also, that no scrap is intended to be mixed with the percentages of silicon given. Should it be desirable to mix scrap with the pig, which, of course, if not Bessemer scrap, would raise the phosphorus, to take the mixture out of the category of Bessemer iron, and in either case with any kind of scrap, it would call for an increase of silicon in the pig metal, so as 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     "