Bulletin . g. 32) consisted ofa rod of Swedish iron, «, 6| incheslong and 1 inch in diameter, uponwhich were wound 250 feet of No. 18B. & S. gage insulated copper annun-ciator wire, b, in 10 layers, the wholebeing covered with electricians tapeto keep the wire in place. The fusedcone was placed in the copper , which was free to swing on a threadsupported from above. A current of3^ amperes was used to energize themagnet. A dilute solution of copper sul-phate was poured over a freshlyground surface of a fused cone. Me-tallic iron was then easily detected when this surface was examinedun
Bulletin . g. 32) consisted ofa rod of Swedish iron, «, 6| incheslong and 1 inch in diameter, uponwhich were wound 250 feet of No. 18B. & S. gage insulated copper annun-ciator wire, b, in 10 layers, the wholebeing covered with electricians tapeto keep the wire in place. The fusedcone was placed in the copper , which was free to swing on a threadsupported from above. A current of3^ amperes was used to energize themagnet. A dilute solution of copper sul-phate was poured over a freshlyground surface of a fused cone. Me-tallic iron was then easily detected when this surface was examinedunder the microscope, as any particles of iron became copper plated. TEMPERATURE MEASUREMENTS. Most of the temperature measurements were made with a thermo-element of platinum and platinum-rhodium and a Siemens andHalske high-resistance millivoltmeter. The cold junction was keptat the temperature of melting ice. The thermoelement was protectedfrom the furnace gases by a glazed Marquardt porcelain tube of. FlGCKE 32.—Electromagnet used todetermine magnetic properties offused cones. 96 FUSIBILITY OF COAL ASH. five-sixteenth inch external diameter. This outfit could be safelyused up to temperatures of 1,550° C. For higher temperatures anoptical p3rometer of the Holborn-Kurlbaum type was used. The ac-curacy of both the thermocouple and the optical pyrometer waschecked at regular intervals by determining the melting points ofgold (1,063° C), diopside (1,391° C), and nickel (1,450° C), as inthe earlier experiments. The whirling flame produced by the three tangential burnersheated the muffle crucible so evenly that it was difficult to see thecones and observe their deformation until means was provided forlocally cooling the cones slightly below the temperature of thecrucible wall. For this purpose a £-inch Marquardt porcelain tubewas inserted through the openings provided for the thermocoupletube: the tube was so placed that when it was connected with thecompressed-air pipe a je
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
