File:The magnetization of cobalt as a function of the temperature and the determination of its intrinsic magnetic field (1911) (14775323764).jpg

Identifier: magnetizationofc00stif (find matches)
Title: The magnetization of cobalt as a function of the temperature and the determination of its intrinsic magnetic field
Year: 1911 (1910s)
Authors: Stifler, William Warren, 1883-1954
Subjects: Cobalt Cobalt Magnetic induction Cobalt Magnetic fields Theses
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Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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43 cm. Three layers of mica were used to separate the two layers.Primary heating coil. Wound on fused silica tube in two layers. FirBt layer, 19 turns of No. 13 nickel wire on 5*5 cm. length.Mean diameter 1.4£ cm.Second layer 17 turns on 5*0 cm. length.Mean diameter 2.0 cm.Secondary heating coil. 10 turns on 4.£ cm. length.Mean diameter 2.6 cm. Mica was used as insulation between the layers and coils.Correction for magnetic field due to heating currents when coilsare connected in opposition = 1-j - 2,6 I2 • The heating coils on the apparatus for the high temper-atures burned out several times. They were rebuilt each time withsubstantially the same dimensions as those given in the table.The induction helix was not injured in any way during the experi-ments. Figure 5 shows the furnace and magnet in position. Temperature Measurements. Temperatures were measuredwith a thermocouple, A Wolff potentiometer and Weston standardcell were used to measure the e,m.f. The resistance in the gal-
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- 22 - variometer oirouit was adjusted ao that the instrument read directlyto one microvolt. The method of reading and calibration was es-sentially that described by Clement and Egy?^ For temperaturesbetween 100°C and 420°C, a copper-platinum thermocouple was used.As this has an inversion point at about 6o°C, it was calibratedabove 100°C. Besides the boiling point of water and the freezingpoint of zinc, several intermediale points - lying between 120°Cand 250°C - were determined by comparison with a carefully cali-brated mercury thermometer. The temperatures were read from thecorresponding e.m.f.s by a calibration curve plotted to such ascale that 1 mm. corresponded to 1°C. A reduced copy of thiscurve is given in Figure 6. For temperatures above 420°C, a platinum platinum-rhodiumcouple was used. This was calibrated at the freezing points ofzinc, silver, and copper. From these three known temperatures thethree constants of the standard parabolic equation were calculated.The cou

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