TEMPERATURE ON TBE MAGNETIZATION OF STEELS, ETC. / 



In order to avoid external disturbances, the observations were 

 made during the night. The scale readings could be easily read 

 to cb of a mm., which corresponded to ca. 4.6 C.G.S. in the 



intensity of magnetization, but it was impossible to read the 

 D'Arsonval galvanometer more accurately than to within a few 

 degrees of the centigrade scale, when temperature was above 700,° 

 although the fluctuations were generally slow. 



It may here be mentioned that a magnetometric study on 

 the effect of temperature on the magnetization of basalt has been 

 made recently by Allan, 1 ' although the heating was done with 

 electricity. 



§3. As the results obtained with iron ovoids do not differ 

 particularly from those already obtained by Hopkixson 2 ', Curie' 

 Lypall and Pocklngton, 41 Morris, 5) and Wills,' !) we shall 

 describe only our experiments with steels, nickel and cobalt. 



Sleek. Ordinary steel behaves qualitatively like iron, with 

 the only difference that the transformation takes place at a higher 

 temperature. Up to about 500°, the diminution of magnetization 

 due to temperature rise is generally insignificant, but with in- 

 creased temperatures the rate of diminution gradually increases 

 till it approaches the critical temperature, which lies very close 

 to 820°. 



In cast steel, the same course as for ordinary steel is repeated 

 at a somewhat higher temperature. The critical temperature 

 of the specimen which we experimented with, was about 920°, 

 being about 100° higher than that for ordinary steel. 



1) Allan, Phil. M«rj. Jan. 1904, \>. 45. 



2) HOPKINSON, loc. cit. 



;'>) Curie, lor. cit. 



4) Lvdall and Pocklington, Proc. R S., 52- 213. 1892. 



5) Morris, Phil. Mag. Sept. 1897, p. 229-230. 



6) Wills, Phil. .Vag. July 1900. p. 1-43, 



