Longitudinal Stress on the Magnetization of Nichel. 123 



cyclic twisting depart more and more from any slight resem- 

 blance which at small loads it seemed to bear to the manner 

 of change for iron. For still smaller loads, then, it might be 

 possible to obtain the magnetization-cm've just opposite to 

 that of iron. 



In the second series of experiments the strength of the field 

 was raised to 2'47 units. The load at first applied was only 

 the weight of the brass wire attached to the lower end of the 

 nickel wire, and a brass rod which gripped the wire during 

 the process of twisting. This load was "02 kilog., that is, a 

 tension of 2*6 kilogs. weight per sq. centim. With this 

 amount of longitudinal stress, the successive twistings and 

 untwistings were performed seven times, and the following 

 readinofs of deflexion were taken : — 



Twist (positive). 



Eeadings. 



Twist (uegative). 



Eeadings. 



o 





o 









148-7 







1480 



20 



166-4 



20 



167-4 



40 



181-5 



40 



183-5 



60 



193-2 



60 



195-3 



80 



201-1 



80 



202-9 



100 



205-9 



100 



208-0 



120 



209-0 



120 



210-0 



140 



210-3 



140 



211-1 



160 



210-9 



160 



211-5 



180 



211-0 



180 



211-6 



160 



207-4 



160 



207-9 



140 



201-8 



140 



2020 



120 



192-5 



120 



193-4 



100 



177-2 



100 



17S-3 



80 



157-3 



80 



1.57-6 



60 



136-6 



60 



137-5 



40 



126-9 



40 



127-0 



20 



133-0 



20 



132-2 







148-0 







1 



148-0 



The curve thus obtained (see fig. 5) is nearly perfectly sym- 

 metrical with respect to the line of zero twisting. Also, the 

 magnetization remains positive throughout the whole cycle. 

 It is, moreover, interesting to observe that the curve is exactly 

 the reverse of that of iron as obtained by Thomson. This 

 shows that the behaviour of nickel twisted in a magnetic field 

 under feeble loads is opposite to that of iron. 



When the stress was increased to 145 kilogs. weight per 

 sq. centim., the magnetization- curve lost its symmetry and 

 became as shown in fig. 6. The intensity of the magnetization 

 became greatly diminished, but still remained positive through- 

 out the whole cycle of opei-ations. The features to be noted 



