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XXXVII. The Anhysteretic Magnetic Properties of Iron and 

 Nickel. Part I. The Relation of Magnetic Intensity to Field 

 Strength and Temperature. By J. Reginald Ashworth, 



D.Sc> 



Index to Paragraphs. 



(1) Introduction and meaning of anhysteresis. 



(2) Methods of suppressing hysteresis. 



(3) Experimental considerations. 



(4) Choice of suitable alternating current. 



(5) Law of inverse relationship between strength of alternating- 



current and intensity of magnetization. 



(6) Construction of anhysteretic isothermals for iron and nickel. 



(7) Construction of anhysteretic isodynamics for iron and nickel. 



(8) Suppression of the critical temperature in nickel. 



(9) Application of Frolich's equation to anhysteretic isothermals and 



the proportionality of his constant to the absolute temperature. 



(10) Discussion of the equation and the relationship of Curie's Constant 



to the ferro-magnetic Constant. 



(11) Analogy to van der Waal's equation to the fluid state. 



(12) Comparison of the effects of alternating Currents and Temperature 



as evidence for a kinetic theory of magnetism. 



(1) npHE phenomenon of hysteresis so greatly obscures the 

 _L magnetic properties of a ferro-magnetic substance 

 that it would appear desirable to eliminate it, or at least 

 reduce it to a negligible quantity in making a study of these 

 properties. In this paper I have confined myself to an 

 investigation of the relation of magnetic intensity (I) to 

 field (H) and temperature (T) when hysteresis is suppressed. 

 This state has been called by M. Charles Maurain " anhys- 

 teretic," and I have adopted this term for the condition in 

 which hysteresis is under restraint without implying that it 

 is altogether absent. 



(2) For the purpose of reducing hysteresis several 

 methods may be employed : the material may be subjected to 

 vibrations and in the case of very soft iron this is effective ; 

 or alternating, or interrupted, currents may be used, the 

 current being made either to traverse the substance under 

 test, or to circulate round it, by running it through a 

 solenoid ; or again the temperature may be raised and lowered. 

 In what follows, an alter Dating current was always employed 

 for the suppression of hysteresis, its advantage being that it 

 can be applied in a definite quantitative manner, and it does 

 not affect the physical structure of the material. 



The current, which was kept in action for the whole course 

 of an experiment, was made to traverse the length of the 



* Communicated by the Author. 



