Relation of Sulpher to the Overpoling of Copper ? Discussion

PHILIP L. GILL, New York, N. Y. (written discussion*).There is one feature of the fire-refining of electrolytic copper which I believe should be mentioned when the relation of oxygen content to the "pitch" or "set" of refined copper is under discussion; that is, the segregation of impurities. Variation of "pitch" or "set" is frequently noted in castings of different shapes, cast at the same time from the same furnace, though the oxygen content remains identical. For instance, it is possible to cast two wire-bars in the same shaped molds from the same ladleful of copper, the one 2 in. thick showing a good level set, the other, 4 in. thick, being overpoled. Also, when two bars are cast of the same weight and at the same time from the same furnace, one bar in a copper mold at the proper temperature, the other in a mold that has been allowed to get overheated, the bar in the hot mold will show