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APPEARANCE OF THE FRACTURE OF PIG IRON. 167
ing mixtures is based on the belief that the appearance of pig fractures, or their hardness, truly defines the character of iron as to the degree of hardness it will give in castings. The founder's own experience in knowing that he can make soft and hard castings from the same ladle, and at one pouring, if he choose to so
construct his molds as to make a difference in the casting rate of cooling, should be sufficient to prove to him why it is possible for two furnace casts of pig metal that are alike in chemical analysis, or will give the same results when melted, to differ so widely in appearance that a fracture from one furnace cast will seem close-grained or hard in the pig, while the other will be the reverse. A founder can take the same ladle of iron, and by pouring part of the metal into a sand mold and part into one that willf charging, etc., to make excuses for his ill results, and not until such a paper as this, exposing the true cause of his trouble, might by chance fall into his hands is there any hope of his being made a follower of the new-school practice.