The magnetization of cobalt as a function of the temperature and the determination of its intrinsic magnetic field . The temperatures were read from thecorresponding 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 couple as used was easily sensitive to 1 mi
The magnetization of cobalt as a function of the temperature and the determination of its intrinsic magnetic field . The temperatures were read from thecorresponding 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 couple as used was easily sensitive to 1 microvolt - equivalentto about °C - at 1100°C. The temperatures as read from eithercouple are probably accurate to 1°C. Preparation of the Cobalt Ellipsoids. - * - The first samples of cobalt obtained were in the form ofsmall lumps 3 or 4 mm. in diameter. Several -attempts were madeto fuse these into a button, using first a small assay furnace andlater a coke furnace. These attempts proved futile owing to thevery high melting point - 14#9f£°C 23. Univ. of Til. Eng. Exp. Station Bulletin No. 36. (1909).. - 24 - After one or two preliminary trials, a button weighingabout 200 grains was prepared, by the Goldschmidt process. Fromthis, two rings were turned and tested by the ring method. Thetests on the larger ring - No. 1 - gave values of B of only aboutone tenth the magnitude to be expected. Annealing for severalhours at white heat improved this decidedly though the resultswere still smaller than the accepted values. The smaller ring -No. 2 - gave fair results without annealing. The results of thesetests are shown in Figures 7 and £. Analysis showed that thesamples contained about \i of aluminum. One hundred grams of cobalt in rectangular sheets about6 cm. x 10 cm. x cm. were later obtained from Kahlbaum throughEimer and Amend. Tests on a ring - No. 3 - made by building upfive layers of this showed that its magnetic properties were ex-cellent. See Figure 9. To get th
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