THE MELTING POINT OF CAST IRON. 347 with asbestos to insulate them from each other and from the iron frame, as well as to serve as a protection in case the tip breaks while in the molten iron. The FIG. 66.-- METHOD OK USING IN LADLE. interchangeable connection holding the clay tip allows it to point out straight for use in small ladles or in experimenting, or it may come down at right angles for taking temperatures in large ladles full of metal.of which is of platinum, the other of an alloy of platinum and 10 per cent, of the rare metal rhodium, cannot be immersed directly in the melted iron — there would soon be an end to this expensive thermo-couple. The long porcelain tube which protects it when used in kilns is worse than useless in a ladle full of metal, and so at the suggestion of the writer the Pittsburg representatives, the Vulcan Mfg. Co. set about to remedy the matter and devise some protective cover which would allow experiments of this kind to be carried out readily. The outcome, while not having the advantage as yet of an extended period of trial, was nevertheless so happy a solution that it is presented, for the first time, with the hope that much of value may be learned from it, not only in our daily work but also in connection with the many intricate problems still before us which await solution at the hands of those willing- to give their time and energy to such an exacting study.