1890.] 



Magnetism and Recalescence. 



443 



FIG. l. 



therefore, qualitatively as regards its absorption or liberation of 

 heat. 



In fig. 2 are the results for a ring containing 0'3 per cent, of carbon 

 or thereabouts. In this case only a cooling curve was taken. It -will 

 be observed that there is a considerable liberation of heat, beginning 

 at 2 h. 12 m., temperature 715 C., and continuing to time 2 h. 22 m., 

 temperature 660 C., being apparently somewhat slower at the end. 

 This may, however, be only apparently slower, as the furnace tem- 

 perature would fall lower in relation to the ring. At time 2 h. 22 m., 

 temperature 660 C., the rate of liberation becomes much more rapid, 

 so much so that the temperature for a time remains almost stationary. 

 At time 2 h. 29 m. the liberation of heat appears to have ceased and 

 the normal cooling to continue. Now, comparing the kicks of the 

 galvanometer, which are proportional to the induction, we observe 

 that the ring begins to be magnetisable at time 2 h. 12 m., its 

 magnetic property increases till time 2 h. 22 m. ; after this point the 

 magnetisability increases much more rapidly, and is practically 

 fully developed at 2 h. 31 m. In this case the development of 

 magnetic property follows precisely the liberation of heat, 

 observed both at the temperature of about 700 C. and at 660 C. 

 We may, therefore, be certain, that both at the higher and lower 

 temperatures of recalescence there is magnetic change, and that the 

 one is as much dependent on the other as the solid condition of ice is 

 upon the liberation of heat when water solidifies. The two changes 



