The London, Edinburgh and Dublin philosophical magazine and journal of science . necessary to reduce the sensibility of theapparatus by using a rotating cylinder of thicker in the case of the change of elasticity, we again observein the metal a singular phenomenon that the change oftorsion by magnetization alters its sign as the magnetizingforce is increased. The results are graphically drawn infig. 8. In weak fields the deflexion shows a further twistingof nickel, that is a decrease of rigidity. This decreasereaches a maximum as the field becomes stronger ; it thenbegins to decrea
The London, Edinburgh and Dublin philosophical magazine and journal of science . necessary to reduce the sensibility of theapparatus by using a rotating cylinder of thicker in the case of the change of elasticity, we again observein the metal a singular phenomenon that the change oftorsion by magnetization alters its sign as the magnetizingforce is increased. The results are graphically drawn infig. 8. In weak fields the deflexion shows a further twistingof nickel, that is a decrease of rigidity. This decreasereaches a maximum as the field becomes stronger ; it thenbegins to decrease, and in a field of about 100 unitsthe rigidity returns to its original value. When the field isfurther increased the rigidity rapidly increases, and then itsrate of increase becomes gradually less. Thus the characterof the change is quite analogous to that of the change ofelasticity. Rigidity of Ferromagnetic Substances by Magnetization. 545 In a given field the change of rigidity is independent ofthe twisting couple. It is also a proof of the same fact that Fig. the curves corresponding to different couples pass through apoint on the axis of the field. The ratio of the change to themodulus itself for different fields is given in the followingtable and in fig. 4. H 20. 40. 80. 100. 200. 400. 600. 800. — xlO2. .-0-96 -1-68 -0-67 0-12 263 5-32 6-67 7*48K Thus in nickel the change of rigidity is considerably largercompared with other ferromagnetics. The nickel rod usedin the preceding experiment was turned into a square rodfrom a plate, and the mechanical process, which the specimenunderwent, hardened it in magnetic quality. If we studythe change of elasticity with the present sample the propor-tionally large change would be observed. According to Profs. Nagaoka* and Zehnderf the mag-netization of nickel increases by twisting in weak fields; instrong fields, however, it diminishes by twisting. Theseresults are reciprocally related to ours. The change of twist so fa
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