

222 Molecular Theory of Induced Magnetism. 



in experiments with nickel wire under twist or under a com- 

 bination of pull and twist. It also agrees with what little is 

 known as to the influence that previous magnetization in one 

 direction has upon subsequent magnetization in another 

 direction. 



To sum up, I have endeavoured to show : — 



(1) That in considering the magnetization of iron and other 

 magnetic metals to be caused by the turning of permanent 

 molecular magnets, we may look simply to the magnetic 

 forces which the molecular magnets exert on one another as 

 the cause of their directional stability. There is no need to 

 suppose the existence of any quasi-elastic directing force or of 

 any quasi-frictional resistance to rotation. 



(2) That the intermolecular magnetic forces are sufficient 

 to account for all the general characteristics of the process of 

 magnetization, including the variations of susceptibility which 

 occur as the magnetizing force is increased. 



(3) That the intermolecular magnetic forces are equally 

 competent to account for the known facts of retentiveness and 

 coercive force and the characteristics of cyclic magnetic 

 processes. 



(4) That magnetic hysteresis and the dissipation of energy 

 which hysteresis involves are due to molecular instability 

 resulting from intermolecular magnetic actions, and are not 

 due to anything in the nature of frictional resistance to the 

 rotation of the molecular magnets. 



(5) That this theory is wide enough to admit explanation 

 of the differences in magnetic quality which are shown by 

 different substances or by the same substance in different 

 states. 



(6) That it accounts in a general way for the known effects 

 of vibration, of temperature, and of stress upon magnetic 

 quality. 



(7) That in particular it accounts for the known fact that 

 there is hysteresis in the relation of magnetism to stress. 



(8) That it further explains why there is, in magnetic 

 metals, hysteresis in physical quality generally with respect 

 to stress, apart from the existence of magnetization. 



(9) That, in consequence, any (not very small) cycle of 

 stress occurring in a magnetic metal involves dissipation of 

 energy. 



