46 PROFESSOR C. G. KNOTT ON MAGNETIZATION 
resistance change and the temperatures in the various fields. These sets of curves, 
marked b, a, are given in the accompanying Plate. 
The first obvious result is the diminution of the resistance change in the higher 
fields as the temperature rises. Thus the effect in various fields at temperature 15° is 
from 200 to 300 times the effect at temperature 342°. So rapid is the final drop above 
300° C. that we may safely regard the effect as practically non-existent at temperature 
350°C. It is just at this temperature that nickel loses its strong magnetic properties, 
RESISTANCE CHANGES ACCOMPANYING MAGNETIZATION OF NICKEL 
AT HIGH TEMPERATURES 
Temperature 100° 200° j 300° 
the permeability being practically unity. Thus we learn that the change of resistance 
of nickel wire due to the application of a longitudinal magnetic field is mainly a 
function of the magnetization or induction in the material, and not of the magnetizing 
force. 
In fields below 5, there is first increase of the resistance change as the temperature 
rises. In fact, all the isothermals from 65° to 300° begin above the isothermal of 15’, 
and then cross it as the field increases. This is particularly well marked in the case of 
the isothermals 65°, 125°, and 180°. This phenomenon may be connected with the 
fact that, up to a certain limit, the induction curve for nickel rises more abruptly 
and reaches its ‘wendepunkt’ in lower fields the higher the temperature. In other 
