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AFFINITY   OF   IRON   FOR   SULPHUR.                  225
32, can be seen in Fig. 102, Chapter LX., page 473.
Iron absorbs sulphur most readily from .the fuel when being re-melted. I have records of its increasing the percentage of sulphur in one re-melt from .030 to .105, with fuel below one per cent, of sulphur, and the iron charged averaging about 1.60 of silicon.
It is no uncommon occurrence for iron to be as high as three to four per cent, in silicon and to contain as high as .200 in sulphur, thereby proving that iron can be high in sulphur and at the same time high in silicon.
While sulphur can increase the strength of iron up to a certain limit, it is of such character as to greatly decrease resistance to deflection or elasticity of iron. On this account I would say that in such castings as chill rolls and ingot moulds, which have their surface and body subjected to high heat, requiring conditions in metal to admit of expansion and contraction following each other closely, excessive sulphur is to be guarded against, and in light or medium machinery it is injurious by increasing the contraction and chill or hardness of castings. The former element is injurious in causing internal strains, and the letter in causing castings to be harder than desired.
It is now (1901) universally conceded that iron has a great affinity for sulphur, and that it is an element often to be feared by both fumacemen and founders. The distribution of the first two editions of this work has done much in advancing the universal recognition of these two facts. .   have found it to increase the strength only from 150 to 200 pounds,   thus   showing that the   higher   the silicon, the less effect the sulphur has in strengthening the iron to the limit of its absorption.    Views of the fracture of the  above  bars, described in Tables 31   andthe so-The philosophical explanation of this extraordinary effect i my opinion, to be found in the fact that the f erro-manganesu .ğR. C. Hindiey, M. Hoskins, Harvard College, Havemeyer University, Henry Hiels Chemical Co., Isabella Furnace, Iron Gate Furnace, Iroquois 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-