ox THE MAGXE']"IZATIOX AXD KETEX'J'IVKXESS OF XICKEL. 307 



way thiit above a certain field (27.6) the twisted nickel ha-s a smaller 

 susceptibility tban the untwisted. Thi.s is shown by the curve (h) 

 crossing the vuwe(a) at this particular field. 



The wire Avas now demas'netized, and twisted throuofh an ancle 

 of 80°, that is 2° per cm. The magnetization curve obtained in this 

 state is shown graphically in Fig. Ifoj. Tlie chief characteristics 

 I'emain the same as forfh); but the "Wendepunkt"' occurs sooner, 

 and the curve rises niore abruptly to this point than for the case of 

 smaller twist. Another thing to be remarked is the increase of resi- 

 dual magnetism. For the untwisted nickel, the ratio of the residual 

 to the induced magnetism is .75 for S^ = 29 ; fov the wire twisted 

 through an angle of 1° per cm. it is .95 ; and f jr the twist of 2° per 

 cm., it is .96. For a twist of 120^ or 3° per cm. these charactei'istics 

 acquire the maximum condition ; the curves of magnetization rising 

 less abruptly, and the maximum susceptibility as shown by the 

 " Wendepunkt " becoming smaller, when the twist is increased to 4°. 5 

 per cm. A twist of 9° per cm. still further diminishes this abruptness ; 

 but the recovery of the wire towards the original magnetic condition 

 in the untwisted state is very slow. Indeed at all twists the magnetiz- 

 ation curve presents much the same characteristics. The general 

 results of these experiments are as follows. Nickel wire twisted 

 under no load acquires its maximum susceptibility in a particular 

 field of force, which is a function of the twist, and is a minimum for 

 a twist of 3° or 4° per cm. In other words, if we draw a line from 

 the origin to the " Wendepunkt," the line (the tangent of whose in- 

 clination gives the maximum susceptibility) is, so to speak, gradually 

 deflected to higher inclinations as the wire is twisted up to 3° or 4° 

 per cm. It then begins to move back again in the direction of its origi- 

 nal position, but very slowly, so that there is not very much difference 

 in the curves for highly twisted wii'es and a moderately twisted 



