The London, Edinburgh and Dublin philosophical magazine and journal of science . p. 459. Rigidity of Ferromagnetic Substances by Magnetization, 541 produced torsions proportional to|their respective weights, thefriction at the pivot does not seem to disturb our results. The examples tested were the same as used in the pre-ceding experiment, except the nickel rod. In the present ex-periments the length of each rod was reduced to 22 cms., andthe diameter of the cobalt bar also to 1*082 cm. The nickelrod used in the last experiment was not sufficiently thick forthe torsion experiment, so that ano
The London, Edinburgh and Dublin philosophical magazine and journal of science . p. 459. Rigidity of Ferromagnetic Substances by Magnetization, 541 produced torsions proportional to|their respective weights, thefriction at the pivot does not seem to disturb our results. The examples tested were the same as used in the pre-ceding experiment, except the nickel rod. In the present ex-periments the length of each rod was reduced to 22 cms., andthe diameter of the cobalt bar also to 1*082 cm. The nickelrod used in the last experiment was not sufficiently thick forthe torsion experiment, so that another nickel bar, whosediameter was 1*117 cm., was substituted for it. Our apparatus was not suited for the absolute measurementof the modulus of rigidity, and therefore its determinationwas carried out in the usual manner with Prof. Nagaokasapparatus above referred to. The results were:— Soft iron. Steel. Wolfram steel. Nickel. Cobalt. Rigidity 7-92 xlO11 7*89 xlO11 8-57 X 1011 7*41 x 1011 6-04 xlO11 4. Soft Iron.—The results of observation are given in fig. Here ordinates represent the change of twist due to mag-netization given in seconds of arc, taken positive when thechange indicates an increase of rigidity and taken negativewhen it indicates a decrease; abscissae represent the effectivefield. N is the moment of force expressed in units. From the figure we see that the untwisting o£ the rodalways increases with magnetizing force, its amount increas-ing in the same way as the intensity of magnetization withincreasing magnetizing force. As the moment of force in-creases the amount of untwisting increases proportionally, sothat the change of rigidity is fairly independent of the twist-ing couple for all magnetizing fields. The form of thecurves is similar to that of the curves of depression in theformer experiment, except in very weak fields. In the pre-sent case the initial minute depression of the curves was notobserved. The angle of torsion, as cal
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