Magnetic Field on Metallic Resistance, 739 



obvious explanation of this for the first two is their magnetic 

 properties, but several reasons militate against this. 



If the magnetic properties were the origin of the effect 

 one would expect a far greater effect in the case of iron 

 than in the case of nickel, but such is not the case. More- 

 over the magnetic properties reach saturation values at field 

 strengths which give no saturation value to the resistance 

 effect. Both the magnetic properties and the resistance 

 effect may be due to the ease with which structural alterations 

 take place in metals which give large effects, but the one is 

 probably not the cause of the other. The dimensional change, 

 the resistance effect and the magnetic properties may be due 

 to a structural alteration such as is given in a longitudinal 

 field. In addition to this it is possible that when the electric 

 field is on and the doublets are orientated transversely to the 

 magnetic field, then a further steady and continuous structural 

 alteration takes place, which gives rise to an increase of 

 internal radioactivity and a consequent diminution of 

 resistance. 



Summary. 



i. Hysteresis curves for both longitudinal and transverse 

 fields at different temperatures have been obtained. 



ii. The effect in a transverse field is shown to consist of 

 two parts, one of which gives an increase and reaches 

 a maximum, and a second which gives a decrease and 

 does not reach a maximum. 



iii. The longitudinal effect and the first part of the trans- 

 verse effect possess similar characteristics. 



iv. There is some relation between the dimensional change 

 in a magnetic field and the resistance effect but one is 

 not the cause of the other. 



v. Both are probably resultant on a structural alteration. 



vi. The ordinary theory for the effect in a transverse field 

 does not explain the results obtained. The effect is 

 possibly due to a further structural change. 



In conclusion I wish to express my thanks to Dr. Hicks 

 for his interest in the work and for kind permission to use 

 his laboratories. 



My thanks are also due to Professor Sir J. J. Thomson 

 and Dr. Swarm for their interest in the work. 



Cavendish Laboratory, 

 Cambridge. 



