THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



APRIL 1900. 



XXX. On the Change of Volume and of Length in Iron, Steel, 

 and Nickel Ovoids by Magnetization. By H. Nagaoka 

 and K. Honda *. 



IN our foimer paper t we have described some effects of 

 magnetization on the dimensions of nickel and iron, as 

 well as those of hydrostatic pressure and longitudinal pull on 

 the magnetization. We have shown that there is reciprocal 

 relation between the two, and that the Yillari effect in iron 

 is a natural consequence of the observed changes of dimen- 

 sions. Unfortunately the range of the magnetizing-field was 

 limited to a few hundred c.G.s. units, so that the investig- 

 ation of the behaviour of these metals in high fields was 

 reserved for further experiments. In addition to this, the 

 ferromagnetics were not of the shape to be uniformly mag- 

 netized, with the exception of iron ovoids. It was therefore 

 thought desirable to repeat the experiment on ovoids of 

 ferromagnetic metals, and to extend the investigation into still 

 stronger fields. 



In his well-known researches on the changes of dimensions 

 of iron and other metals by magnetization, Bidwell \ pushed 

 the field-strength to 1500 ; in the present experiment the 

 field-strength is greater than that of Bidwell by 700. In 

 addition to ordinary soft iron and steel ovoids, wolfram steel, 

 from Bohler, in Vienna, was tested, with a result which 



* Communicated bv the Authors. 



f Nagaoka & Honda, Phil. Mag. vol. xlvi. p. 262 (1898). 



J Bidwell, Phil. Trans, vol. clxxix. p. 205 (1889). 



Phil. Mag. S. 5. Vol. 49, No. 299. April 1900. 2 A 



