ox THE MAGNETIZATIOX AXD RETEXTIVEXESS OF XICKEL. 319 



through 1°.5 per cm. is sufficient to increase tlie maximum retenti^■e- 

 ness more than 6 times for afield of 27, althougli the absohite vahie 

 of tlie residual magnetism falls far short of the values obtained for 

 small longitudinal stresses. Tiie maximum value of the ratio of the 

 residual to induced magnetism is .90 for a twist of 4°.5 per cen. These 

 phenomena are represented in Fig. 7.,, 7i„ 7^. 



All these curious properties of the twisted nickel must be ac- 

 counted for by the change of molecular structure caused by the 

 torsional stresses. But as we know nothing regarding molecular 

 arrangements, we can make no definite assertion how the chantée 

 takes place. We may however conceive the wire in the normal state 

 as consistino- of an assemblage of rows of molecules arranj^ed in 

 a straight line along the lenj^th of the wire. On twisting the wire, 

 these rows or filaments of molecules will no longer be straight, but 

 will become a spiral. Since all such molecular filaments in the wire 

 sutler similar distortion, the axes of the molecules in the unmagnetized 

 nickel will be iudifterently placed in all directions either in the normal 

 or the twisted wire. Now if the wire is magnetized longitudinally, 

 the magnetizing force will be parallel to the molecular filaments in 

 the untwisted wire, but in the twisted wire the corresponding mole- 

 cular filaments will no longer be parallel to the magnetizing force. 

 Such considerations would lead us to expect distinct differences in the 

 curves of magnetization for the two states of nickel. 



If, according to Weber's theory, the application of a magnetiz- 

 ing force tends to turn the axes of the molecules in one direction, t\w 

 results of my experiments show that the twist applied to the wire 

 makes the molecules turn more easily. There also exists a critical 

 value of twist, beyond or below which the molecules turn with less 

 ease. This twist is about 3° per cm. in the wire experimented, lîut 

 in spite of the ease of the molecules in tiu-ning, they seem to be nn- 



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