ON MAGNETOSTRICTION. 



33 



(/>) AiiiKinlcd cobnit contracts in volume at a steady rate as 

 the field is increased. The contraction becomes ultimately f^reater 

 than in cast cobalt. 



o. The increase of volume in 4ö% Ni, ;U)% Xi, and 29% Ni 

 steels takes place almost proportional to the strength of the üeld. The 

 amount of the increase becomes greater as the percentage of nickel 

 becomes less. The volume change in 29% Ni is the greatest that has 

 ever been observed, and is nearly 40 times that in iron in strong 

 tields. 



Wiedemann Efect. 



The torsion produced by the combined action of circular and 

 Longitudinal magnetizations in nickel steels increases with the lonofitu- 

 dinal field and reaches a maximum whence to decrease gradually 

 as the field is further increased. In some specimens, the torsion 

 ultimately takes place in the opposite direction. The direction in 

 which nickel steel twists is the same as in iron. 



