CHANGE OF DIMENSIONS BY MAGNETIZATION. 



99 



a phenomenon which is perhaps to be attributed to the residual 

 effect noticed in ray former paper^'. The constancy of the 

 difference in the above table furnishes additional evidence in 

 support of this view. The œolotropy of the tube as regards the 

 change of length evidently influences the experimental values. 

 Moreover tlie change of the intensity of longitudinal mag- 

 netization due to the mutual interaction of longitudinal and 

 circular fields is not taken into account in the calculation of the 

 effective field. These causes, I believe, are sufficient to account 

 for the said discrepancy. 



In steel and soft iron, there are comparatively large diffe- 

 rences between the calculated and the experimental numbers, as 

 will be seen from the following table : 



TABLE X. 



For iron and steel, the sensibility of the apparatus was about 

 2xlO~' and the correction for temperature amounted to 5xl0~^ 



1) K. Hoiidu, Jour. Sc. Coll. XF., 311, 1899. 



