Certain Seasoned Hard Steel Magnets. 



249 



abnormal one gave curves like those of the hundreds of other 

 magnets experimented on. 



Many curves were obtained with rising temperatures, but as 

 has been said these sometimes differ slightly from those made 

 with falling temperatures, unless the magnet has been recently 

 boiled when no such difference appears. In some instances 

 the curve is almost straight from room temperatures up to 

 40° C, and is again nearly straight between 80° and 100°, so 

 that most of the curvature falls between 40° and 80°. 



As fair examples I give (in Tables II, III and IY) the results 

 of observations made for me with great care on three magnets. 

 If the temperatures are used as abscissas and the fractional 

 loss of magnetic moment as ordinates, Tables II and III yield 

 curves which are concave upwards, while the curve obtained 

 from Table IY is nearly straight. These curves are shown in 

 figures 1, 2, and 3. 







1 







0.025 







/ 



0.020 







/ 



0.015 





/ 





O.OIO 



/ 







0.050 



0/2 



/ 



5 



5 



O 



5 100 



