MAGNETIZATrON AND MAGNETIC CHANGE OF LENGTH. 



15 



NICKEL STEEL 24.04%^ 



^=i6.oX 



/=-i86°C 



/ = 30.o°C 



As in the case of iron, tungsten steel and nickel, the mag- 

 netization of the alloys of nickel steels containing percentages of 

 nickel greater than 26.64:% is decreased in weak fields and 

 increased in strong, by cooling them in liquid air. In alloys 

 containing lower percentages of nickel, the magnetization always 

 increases on cooling. The amount of the change of magnetization 

 by cooling is considerably large ; witli the exception of 28.73'?^ 

 nickel steel, it increases as the percentage of nickel decreases, up 

 to 26.64^0. The magnetization in liquid air of 25^^ nickel steel, 

 which is almost non-magnetic at ordinary temperatures, is also 

 very small. As tlie percentage of nickel further decreases, the 

 change of magnetization by cooling again increases. With 26.64?^ 

 nickel steel, which undergoes the greatest change of magnetization 



