ON MAGNETOSTRICTION. 31 



§ 8. Summary of the Results. 



The results obtained in the present investigation can be sum- 

 marised in the following statements. 



Magnetization. 



1. The maoTietization of cast cobalt is différent from that of 

 the annealed metal, the latter being only about half as magnetizable 

 as the former. The magnetization of cobalt in the annealed state is 

 characterized by its high differential susceptibility in strong fields. 



• 2. The magnetization of 4:6% nickel steel is between iron and 

 cobalt, while that of the 36% Xi is nearly the same as in cobalt. The 

 29% Ni is nearly half as magnetizable as nickel, and the 25% Ni 

 is only feebly magnetic. The course of the magnetization curve in 

 nickel steel resembles that in nickel. 



3. (a) In cast cobalt, mechanical elongation in the direction of 

 magnetization produces diminution of magnetization in low fields, 

 which gradually lessens as the field strength is increased. Ultimate- 

 ly there is increase of magnetization by elongation. Thus, there is 

 a critical point in cobalt, which has a character opposite to that bear- 

 ing the name of Yillari in iron. 



(I)) In annealed cobalt, mechanical elongation in the direction 

 of magnetization produces diminution of magnetization, which in- 

 creases with the field. 



4. Mechanical elongîition in the direction of magnetization 

 produces increase of magnetization in nickel steel. 



Change of Leiujtli bij Magnetization. 



1. The quality of the change is not seriously affected by the 

 small non-homogeneity of the sample. 



