Crook — Electromagnetic Alternating Currents. 143 



The curves on Diagram II show that for low current densi- 

 ties, the reduction of the residual magnetism in iron, or the 

 reduction of the area of the hysteresis cycle, is proportioned to 



Diagram VI. 



MUtETT* liaTITUTe Of TEOHKOLOOY, 



the strength of the current. Above 7*5 amperes per sq. mm. 

 this relation does not hold, but heating effects and the effect 



