EFFECT OF TWIST ON THE MAGNETIZATION OF NICKEL AND 1E.ON. lUo 



range oftwist is small, but that when the range is large there is a 

 ' priming ' in magnetization rather than a lagging.* Now we are 

 quite warranted in using the word hysteresis in both senses, just as 

 acceleration in dynamics includes retardation. We may speak of 

 positive and negative hysteresis; and express the phenomenon just 

 described as a reversal of hysteresis, occurring probably at some twist 

 intermediate to the two just named. How this reversal of hysteresis 

 is affected by various conditions such as the quality of nickel, the 

 strength of the magnetizing force, the amount oftwist. &c, is a very 

 obvious matter for investigation. 



Kuccl in stronger fields. — With the same wire and other conditions 

 being the same, the field was taken stronger and stronger. Very 

 similar effects were obtained as may be seen from Fig. '2, which 

 corresponds to a field § = 11.9. In Fig. 3, however, a change 

 begins to shew itself. The field is now 13. <S, and the particular 

 wire examined was a new piece cut from the same specimen. 

 It will be noticed that the range of change is much diminished, 

 but that the character of the hysteresis is still the same as before. 

 When the strength of the magnetizing force is increased to 18.7 

 units, the magnetization curve (Fig. 1) wears quite a different aspect. 

 On first twisting, the magnetization diminishes as in the former 

 cases, but it never passes a minimum, although the rate of fall be- 

 comes very slow towards the limit of twist. On untwisting, (here i> 

 gradual increase of magnetization, but it is always smaller for the 

 same angle of twist, than it was during the operation of twisting. 

 Thus there is hysteresis in the proper sense of the word. Further 

 twisting in the opposite direction produces a similar succession of 

 changes, although the curve is not quite symmetrical about the line 



* t was nut aware, until my own experiments were all completed, that this i>heuomeiioii 

 liât been observed by Mr. Iinagawa. See the precediug paper, by Or. Knott. 



