MAGNETIZATION AND MAGNETIC CHANGE OF LENGTH. 



19 



The hysteresis-loss of nickel steels at ordinary temperature 

 is generally small compared with other ferromagnetic metals. The 

 values for reversible alloys are, however, comparable with those 

 of nickel ; but for irreversible alloys, they are all very small. 

 Especially nickel steel of 28.32 ?« does not almost enclose any 

 area, giving only 16 ergs for an induction of 1200 C.G.S. If 

 the alloy has a greater value for induction, it will be very useful 

 for the construction of transformers. Thus the magnetic state 

 of the irreversible nickel steels corresponds to that of ferromagnetic 

 metals at high temperatures. As seen from Fig. 2 a, the Stein- 

 metz's formula does not apply, except for very weak inductions. 



If the alloys be cooled in liquid air, the hysteresis-loss 

 increases. With irreversible alloys, the increase is enormous. 



