332 H - NA.GAOKA AND K. HONDA; 



The constants of elasticity for nickel are in fair agreement with 

 Prof. Voigt'» 11 determinations, who gives E=2.03xl0 12 , Iv=0.782x 

 10 12 . 



We now possess sufficient experimental data, to calculate the 

 coefficients k' and k". In finding k' and h" from experiments on the 

 effects of stress on magnetization, we shall combine the measurements 

 of the changes produced by pull and by hydrostatic pressure. Taking 

 into account the minuteness of the effect of pressure compared to that 

 of pull, we can greatly simplify the calculation. 



We know that -77— is very small compared to ^— ; we therefore 

 conclude from (e) that in the combination above mentioned, 



whence ( f ) gives for the change of susceptibility due to longitudinal 

 pull 



XE v 



We can thus find k' and //', without further experiment, by measure- 

 ment of the effect of longitudinal pull only. The difference in .the 

 value of k caused by neglecting — — is quite within the experimental 

 error, as will be immediately shown. 



Results in nickel. As the nature of these coefficients is simpler 

 in nickel than in iron, we shall first give the numbers for the 

 former metal. 



The following table contain- the numbers obtained from the 

 experimental curves, and used in the calculation of k' and k" from the 

 strains produced by magnetization. 



1). Voigt, IVied. Ann. 49, 396, L893. 



