*.42 METALLURGY OF CAST IRON.
which came down as hot as is generally required for pouring stove plate.
The 210 analyses shown, along with the extra work of cross-checking, were made by Mr. H. E. Diller, of the Pennsylvania Malleable Co., Pittsburg, Pa. The writer and the association are greatly indebted to Mr. Diller for his work in making gratuitously such a large number of analyses. We have also in this connection to thank Prof. A. W. Smith, of the Case School of Applied Science, Mr. Frank L. Crobaugh, proprietor and expert of the Foundrymen's Laboratory, Cleveland, O., and D. K. Smith, chemist, Claire Furnace, Sharpsville, Pa., for their able services in checking the combined and graphitic carbon determinations, a work done in order to increase the confidence in the determinations of carbon.
The moulding, casting, and testing of the bars were all performed chiefly by the writer, as he believes experimenters should leave as little to other parties as possible. To give an idea of the costs in making experiments, it can be said that if the labor and material involved in this series of experiments were computed at the lowest ordinary rates, the cost would reach about three hundred dollars.
In a general way, the addition of manganese to the iron in the cupola increases the hardness by raising the percentage of combined carbon, which means greater contraction and chill, with a decrease in deflection and elasticity. While it is true that manganese in cupola mixtures has the tendency just mentioned, a study of the tests given in Tables 35 and 36 will show that the variation of manganese generally existing in any one grade of pig iron will have very little if any effect onble 35, two " .401. 1-375 .040 Mottled