Elasticity of Ferromagnetic Substances by Magnetization. 45 



depress the absolute amount of decrease. For a weak tension 

 the elasticity increases by magnetization in fields higher than 

 a certain field at which the change is zero. This field is 

 displaced toward the higher field by the increasing tension. 



The change o£ elasticity calculated from the effect of 

 tensions upon the magnetic change of length is as follows : — 



Table III. 

 AT =743 gr./mm. 



T = 1540 gr./mm. 2 



T=3021 



gr./mm. 2 



T=4498 



gr./mm. 2 



H. 





H. 



TO 



P X 10 2 . 



It. 



■k|l 



20 



- 7-4 







35 



-191 



30 



- 3-1 



40 



- 24 



40 



-17-4 



60 



-14-3 







60 



- 6\o 



70 



-143 



80 



-124 



100 



- 07 



iiO 



- 6 1 



100 



-131 



200 



4- 2-4 



150 



00 



130 



- 76 



300 



4- 3 6 



2. r '0 



+ 1-2 



200 



- 3-8 



380 



+ 35 



350 



J- 2-5 



300 



- 1-6 



Curves are also given in fig. 2 in dotted lines. Comparing 

 the above results with those directly observed, we notice at 

 once that the general course of the change of elasticity is 

 quite similar for both results, the fields in which the change 

 is maximum coinciding in a remarkable way. The amount 

 of the change is generally greater in the present case than 

 in the previous one. 



(ii.) Commercial Nickel. 



PL I. figs. 3 & 4. 



The change of length by magnetization is generally similar 

 to that in pure nickel. But the effect of tension is much 

 smaller, and the field in which the effect of an additional 

 tension is null does not differ so much for different tensions 

 as in the former specimen. The results are given in Table IV. 

 and in fio-. 3. 



