64:6 Messrs. K. Honda and S. Shimizu on 



Annealed Cobalt (cont.). 



*=--1066°C. 



£=1074° C. 



*=1109° C. 



*=1219° C. 



H. 



I. 



H. 



I. 



H. 



I. 



H. 



I. 



2-25 

 7-54 

 46-8 

 149-6 

 244-1 

 436 



25 



44 



62 



87 



100 



107 



7-5 

 41-7 

 172-1 

 343 

 446 



10-6 

 19-4 

 328 

 41-9 

 45 



142 

 324 

 446 



30 

 6-1 



7-7 



130 

 234 

 443 



2-2 

 3-6 

 4-3 



The magnetization of iron and nickel at high temperatures 

 is so well known that it is superfluous to give all the 

 numerical data obtained by our experiments. Hence in the 

 above table, the numbers for iron and nickel are limited to 

 those at very high temperatures, in which they become of 

 interest. 



Swedish Iron. — The magnetization at constant temperature 

 was measured at 20 different temperatures in ascending as 

 well as descending stages ; the curves of magnetization were 

 then plotted against the internal field. These curves were 

 cut by an ordinate of constant field. The curves of magnet- 

 ization in a constant field plotted against the temperature 

 were thus obtained, and are given in fig. 6 a (PI. XI.). 



The change of magnetization of Swedish iron with rise of 

 temperature was found to agree well with the results obtained 

 by previous investigators *. The weak magnetization beyond 

 the critical point, as first observed by Curie, was also noticed. 

 Here the magnetization at different temperatures ranging 

 from 800° C. to 1200° C. diminishes very slightly as the 

 temperature rises. Thus the meaning of the critical point 

 becomes vague ; H. Du Bois defines this temperature to be 

 a point of inflexion in the temperature-curve of magneti- 

 zation ; but it is more convenient to define the temperature 



* J. Hopkinson, Phil. Trans, clxxx. p. 443 (1889) ; Proc. Roy. Soc. 

 xliv. p. 317 (1888). Lydall and Pocklington, Proc. Roy. Soc. lii. p. 228 

 (1893). D. K. Morris, Phil. Mag. xliv. p. 213 (1897). Ledeboer, C. R. 

 cvi. p. 129 (1888). Tomlinson, Proc. Phys. Soc. ix. p. 181 (1888). 

 Curie, C. R. cxv. p. 805 (1892) ; cxviii. pp. 796, 859. Wilde, Proc. 

 Roy. Soc. 1. p. 109 (1891). Kunz, Elekt. Zeits. xv. p. 194 (1894). 

 Wills, Phil. Mag. 1. p. 1 (1900). Nagaoka and Kusakabe, Jour. Coll. 

 Sci. xix. art. 9 (1904). 



