648 Messrs. K. Honda and S. Shirriizu on 



Nickel. — The specimen, which was first cooled in liquid 

 air, was heated, and the magnetizations at ten different 

 ascending temperatures were observed ; since the dynamo 

 stopped when the temperature attained 1150° C, the 

 magnetizations at decreasing temperatures were not taken 

 as in the other cases, except for the maximum field 

 only. 



The temperature-curves of magnetization are drawn 

 in fig. 6 c, in which the results of the first experiment 

 are also included. The character of the change of magnet- 

 ization by heating coincides with the results obtained by the 

 former investigators *. Here the range of the temperature 

 is considerably extended on the negative side of zero tem- 

 perature. It is remarkable that though the magnetization 

 falls very rapidly near the critical temperature 360° C, its 

 further decrease is very small, and even at 1200° C. a 

 magnetization of about 6 c.G.s. for H = 400 is still observed. 

 This important phenomenon was first observed by Curie. 



(b) Magnetization of Nickel-Steels. 



In nickel-steels the magnetic state after cooling in liquid 

 air slightly changes as the time proceeds. In some alloys it 

 does not return to its initial state when they^ undergo a cyclic 

 change of temperatures between —186° 0. and 1100° C. 

 This change of character is greater in the irreversible alloys 

 than in the reversible. 



The magnetization of the alloys at different temperatures 

 presents a striking contrast between the reversible and the 

 irreversible alloys. Some of the interesting results had 

 already been obtained by previous investigators f . 



The manner in which the magnetization o£ the reversible 

 nickel-steels changes with the temperature is similar to that 

 of nickel, as given in Table XI. 



* J. Hopkinson, loc. tit. Curie, loc. cit. Nagaoka and Kusakabe, 

 .loc. cit. 



f H. Becquerel, C. R. xciii. p. 794 (1881). J. Hopkinson, Proe. Eoy. 

 Soe, xlvii. p. 23 (1890) ; xhiii. p. 1 (1890). H. Le Chatelier, C. R. ex. 

 p 283 (1890) ; cxi. p. 454 (1890). H. Tomlinson, Proc. Roy. Soc. lvi. 

 p 103 (1894). F. Osmond, C. R. cxviii. p. 532 (1894) ; exxviii. pp. 304, 

 1396 (1899). Ch. Ed. Guillaume, C. R. exxiv. pp. 176, 1515 (1897); 

 exxv. p. 235 (1897) ; exxvi. p. 738 (1898) ; " Les Aciers au Nickel," 

 Paris (1898). E. Dtimont, C. R. exxvi. p. 741 (1898). L. Dumas, C. R. 

 exxx. p. 357 (1900). 



