64 Profs. J. Dewar and J. A. Fleming. Changes produced in 



liquid air was to cause the magnet to possess a magnetic moment 

 about 10 per cent, greater at 185 C. than at 5 C. It will be seen, 

 therefore, that these steels differ from the chromium steels in this 

 respect, that whereas in the chromium steels the effect of the first 

 cooling is to cause an increase in magnetic moment ; in the case of 

 the aluminium steels, the effect of the first cooling was to cause a 

 decrease of magnetic moment, although much smaller relatively than 

 in the case of the carbon steels. 



Nickel Steels. Experiments were then made with samples of nickel 

 steel containing 0'94, 3'82, 7'65, 19'64, and 29 per cent, of nickel. 

 These steels exhibited some rather interesting peculiarities. In the 

 case of the nickel steel with O94 per cent, of nickel, the effect of the 

 first cooling in liquid air was to cause a very small decrease in mag- 

 netic moment (see fig. 11), and the subsequent heating and cooling 



loo 



So- 



FIG. 11. Nickel steel. 



Ni = 0-94 

 C =0-13 

 Si = 0-23 

 Mn = 0-72 



Fe = 97-98 



brought the steel into a condition in which its magnetic moment, 

 when cold, was always greater than its magnetic moment when warm, 

 by about 10 or 11 per cent. In the case of the nickel steel with 

 3'82 per cent, of nickel, the effect of the changes of temperature 

 was very similar (see fig. 12), and also in the case of the nickel steel 

 having 7'65 per cent, of nickel the order of the changes was not very 

 different in this respect, that the magnetic moment when cold was 



5o- 



FIG. 13. Nickel steel. 

 Ni = 7-65 

 C - 0-17 

 Si = 0-28 

 Mn = 0-68 

 Fe = 91 -22 



