JOURNAL OF THE COLLEGE_OP_SCIENCE, IMPERIAL UNIVERSITY, 

 TOKYO, JAPAN. 



VOL. XIX., ARTICLE 10. 



Change of Length of Ferromagnetic Substances 



under High and Low Temperatures 



by Magnetization. 



By 



K. HONDA, RigaJcuhakushi, 



AND 



S. SHIMIZU, RigaJeushi. 



With Plates I— III. 



The interesting experiments of Hopkinson on magnetization at 

 high temperatures promise us some important results in the magnetic 

 change of length at such temperatures. On account, however, of the 

 experimental difficulties, this interesting subject has as yet scarcely 

 been investigated. Barrett* was the first to touch the subject ; with 

 a rise of temperature of about 50°C, he observed no effect on the 

 magnetic change of length in iron and cobalt ; but in nickel, the 

 contraction was reduced to about two-thirds of its ordinary value. 

 A few years ago, one of usf studied the same effect in iron, tungsten 

 steel, and nickel at temperatures ranging from 18°C to 100 C. In 

 weak fields, the magnetic elongation of iron was slightly diminished 

 by heating ; but in strong fields, it was increased. In tungsten 

 steel, the elongation was always diminished ; in nickel, the con- 

 traction was considerably reduced except in weak fields, in which a 

 minute increase of contraction was sometimes observed. 



* Barrett, Phil. Mag. [4] 47, 51, 1S74; Nature 26. 515, 586, 1882; Beibl. 7, 201. 

 t K. Honda, Jour. Se. Coll. XIII, 83, 1900. 



