EFFECT OF TWIST OX THE MAGNETIZATION OF NICKEL AND IKON. l!Jl 



inents for nickel were performed under low tensions. The effects of 

 torsion on magnetization are much simpler for iron than for niche], 

 vet in both there exists quite a curious change in the hysteresis as will 

 a (»pear hereafter. 



Effect of Twist on the Magnetization of Nickel. 



The effect of cyclic twisting; on the magnetization of nickel wire 



is itself a function of the magnetizing- field and of the range of twist- 

 ing. and passes through a distincj gradation of changes as this range 

 is gradually increased. For small twists these changes are marked 

 by many peculiar and interesting characteristics; and most of my ex- 

 periments are limited to cases in which the twist is not very large. 

 To examine the effect of longitudinal stress on the magnetization for 

 each range of twist and for each magnetic field would be a matter of 

 immense labour. I have therefore examined only a few cases in 

 which the load was varied, and have noted some of the general 

 features. 



Changes of magnetization for (he Hoist of ± 0°.86. — The smallest 

 amount of twist producing changes in magnetization, which could be 

 measured with certainty, was about 0?9 per cm. A nickel wire, 0.43 

 mm. in radius and 35 cms. long, was well annealed, and placed in posi- 

 tion, the longitudinal stress acting being only the weight of the small 

 twisting rod and the brass wire connecting this rod to the lower ex- 

 tremity of the nickel wire. 



The first experiment was performed in a field of Ö.34 (C.G.-S. 

 electro-magnetic unit). The wire was twisted through ± 30° (0?86 

 per cm.) on both sides of the initial unstrained position. After the 

 changes in magnetization became cyclic, the following readings of 

 the deflections were taken. 



