Ï80 



H. XA0A0KA AND K. HONDA; 



The fort nulle (c) (</) are never exact, as prismatic bodies can not 

 be magnetized uniformly, and consequently there must be also internal 

 forces actin f. But to the first approximation we can use these 

 formuhe, inasmuch as (he strain caused by magnetization can only 

 be roughly measured. Mr. Jones 1} employed (a) for a nickel wire ; 

 the difference tz— =- is, however, very small in nickel, so that there 

 will be no great discrepancy in the final result. 



The change in magnetization due to increase of volume a by 

 hydrostatic pressure is evidently 



1 



dl= -H[k'+ 



[v+-^-v)<r, («) 



and the change of susceptibility due to longitudinal stretching / of 

 a prismatic body 



For the determination of the coefficients k' and Jc", the combination 

 of the experimental data in any two sets of the experiment already 

 described can be conveniently used. In order to test Ivirchhotf's 

 theory, we have calculated ¥ and h" from experiments on the change 

 of volume and of length by magnetization, and compared them with 

 values deduced from experiments on the change of magnetization 

 produced by compression and by stretching. Thus, for a prismatic 

 body, we obtain from (c) and (J) 



E 1 



(A) 





for an (.»void, we obtain from (11) and (/<) 



1). E. T. Jones, loc. .-it 



