2 ART. 9. H. NAGAOKA, AND S. KUSAKABE : EFFECT OF 



part qualitative until the decided advance in quantitative deter- 

 mination made by the researches of Hofkinson 11 and Curfe. 2) 

 Although the former used the ballistic method and his magnetiz- 

 ing field was not strong, yet he did not fail to bring to light the 

 principal features of the change in magnetization near the critical 

 temperature. Curie utilized the mechanical force brought into 

 play, when a ferromagnetic body is placed in a heterogeneous 

 field. The magnetization could hardly have been uniform through- 

 out, but the method was well adopted for heating the substance 

 beyond the melting point and for examining its magnetic quality 

 in fields scarcely attainable by means of a magnetizing coil. It 

 would be superfluous to enter into a discussion of the advantages 

 and disadvantages of the methods and arrangements of Hopkinson 

 and Curie, suffice it to remark, that the magnetometric method 

 is after all the best suited for the investigation of the change of 

 magnetization near the critical temperature. We are however 

 beset with difficulties in arranging the magnetizing coil and the 

 heating apparatus within a small compass, so as to insure at the 

 same time, the uniformity of the field and of the temperatures. 



The present paper gives a description of experiments made 

 more than two years ago, for the purpose of studying the tem- 

 perature effect on the magnetization of iron, various kinds of 

 steels, nickel, and cobalt ovoids. The measurement of the intensity 

 of magnetization was made by means of a magnetometer, and the 

 heating was effected by gasflames, instead of following the usual 

 method of raising the temperature by an electric current. 



§2. Method of Experiment. — The method adopted in. the 



lj Hopkins. i\, Phil. Trans, for 1889. p. 443. 

 2) Curie, Ann. de Clüm. et de Phys. 5, 289, 1895. 



:;) An abstract of the paper is given in Reports of the Tokyo Matheraatico-physical 

 Society for September, 1902. 



