THE MELTING POINT OF CAST IRON. 349
gotten up and calibrated for industrial purposes. The original form with the reflecting mirror, and capable of reading to one-half of a degree at these high temperatures, was found too cumbersome and delicate for factory use.
"The sensitiveness of the couple, even though protected by a refractory material, is such that by plunging it cold into the melted iron the correct reading is obtained in one minute and three-quarters. When properly heated up to redness beforehand, however, this time is reduced to not many seconds.
" It would be beyond the scope of this paper to show the many uses to which such an instrument can be put in the steel and iron trade. On the question of annealing alone it will pay for itself in a short time.
"We come now to the subject matter itself. You will all remember the recent discussion on the melting of white and gray irons, Mr. West's elaborate experiments confirming our daily experience. Yet the correctness of the conclusions were questions, and while the peculiar phenomena observed in the behavior of carbon with iron make any positive statements rather hazardous, yet the melting down of a lump of iron, and taking its temperature while doing so, should stand as a final determination of its melting point as viewed from the entirely practical side of the question. This is the consideration we have to deal with daily in cupola and furnace.
"The material experimented with was gathered for several years, some of it being furnished by Mr. Jos. Seaman, Mr. Thos. D. West, and Mr. J. E. McDonald, members of this association, and the especially interesting alloys by Mr. R. McDonald, of the Crescent Steel Co.which runs back, parallel to the platinum wire, to the terminal box. Both wires are covereda short time, compared to that generally occupied in ordinary shop practice. The longer heated or semi-molten iron remains in contact with incandescent fuel or is exposed to gases, the more sulphur will be absorbed — up to the limit of the iron'sding its mate.. 2111 3Os i m. mi 3os 3OS. 3111. im ^os Jill l^S i in.