RESEARCHES OX MAGNETOSTRICTION. - 339 



find it to be about 3.8xl0 5 From experiments on the effect of 

 stretching. 



Summary. 

 We conchide the present paper by giving a summary of the 



results of the research on which it is bused. 



( 1 ) The volume of iron increases by magnetization. 



{- ) Diminution of volume by hydrostatic pressure produces 



decrease of magnetization in iron. 

 ( 3 ) The volume of nickel decreases by magnetization. 

 ( 4 ) Diminution of volume by hydrostatic pressure produces 



increase of magnetization in nickel. 

 ( 5 ) Positive transverse pressure produces increase of magnetization 

 in an iron tube ; the magnetization reaches a maximum in a 

 critical field, thence to diminish gradually (ill it ultimately 

 becomes less than in the unstrained state. 

 The following gives a comparison of Kirchhoff's theory with 

 ex peri 11 lent. 



/. Effects of stress calculated from the strains caused l>u magnetiza- 

 tion. 

 (a) (Theory) Hydrostatic pressure in iron produce: increase of 

 magnetization. 



(Experiment) Hydrostatic pressure produces diminution of 

 magnetization in iron. 

 (I)) (Theory and Experiment) Hydrostatic pressure produces small 



increase of magnetization in nickel. 

 (c) (Theory and Experiment) By the application of a small constant 

 longitudinal pull, there is increase of magnetization in iron 

 till it reaches a maximum in moderate field, thence to 

 diminish till the magnetization becomes smaller than in the 

 unsf retched condition. 



