EFFECT OF MAGXETIZATIOX OX THE PEEMAXEXT TWIST OF XICKEL. 333 



ïlie application of the iiiaii'netiziiiijf force .showed at tir.st an un- 

 twisting, which reached a niaxiniinu in a field strength of ahont 65 

 C. G. S. units. The wire then began to twist. In a field ofal)<)ut 

 335 units, it came back to the condition in which it was after release 

 before the magnetizing force was applied. Thereafter the wire continued 

 steadily to twist with the increase of magnetizing force, so that when 

 §=432, the wire became twisted 10' from its initial position of 

 ec[uilibrium. Thus a nickel wire with large permanent twist can he 

 twisted by applying sufQciently great magnetizing force. As the 

 course of the curve after passing the maximum is less steep in thick 

 than in thin wires, still stnniger magnetizing fields will l)e necessary 

 to twist the former. 



The next set of experiments has to do with nickel wires under 

 longitudinal stress. The only change in the process of experimenting 

 consisted in loadirig the wire. Tlie vane was detached from the lower 

 end of the cross and a short hook placed in its stead. A pan of 

 weights hung from this hcx^k, and was completely immersed in the 

 water. 



