8 AKT. 13.— K. IIOXDA, S. SIIIMIZU AND 8. KUSAKABE : 



From the angle of torsion and its change, we calculated the 

 rntu) of tiie change (dK) to the rigidity (A') itself. The ratio is 

 fairly indei)endent of the twisting couple for all helds ; in the 

 following table, mean values for the different couples are given. 



These values are also plotted against the magnetizing force in 

 Fig. 2 ; the course of the curve resembles that of magnetization, 

 having one inflexion point and approaching to an asymptotic value as 

 the field is increased. 



The untwisting by magnetization forms a reciprocal relation to 

 the well known fact that the magnetization of iron decreases by 

 twisting. 



The above results for soft iron agree in (piality witli those of 

 previous experimenters, and the ain(junt of the change nearly coincides 

 with some of lîarus' results. In the experiment of Day, the change 

 of rigidity was a little smaller than in the present case, and was 

 greatly influenced by the amount c^f the twisting couple in contradic- 

 tion to our results. Stevens' ex])eriment gave a much greater increase 

 of rigidity. 



Wolfram slecL As we have already found the change of elasticity 

 in wolfram steel due to magnetization is nearly the same as that of 

 soft iron both in quality and in t^uantit}'. This remark also applies 

 to the present case, so that what we havci said about the change of 

 rigidity in soft iron equally applies to the case of Avolfram steel. 



This will be seen from the following tables and F'ifjs. 3 and 2 : 



