336 Messrs. Nagaoka and Honda on Change of Volume and 



the intensity of magnetization. As will be seen from the 

 curves (dotted lines in fig. 2), the increase in nickel and steel 

 takes place quite slowly before the magnetization reaches 

 saturation. As soon as the magnetization reaches this state, 

 the increase becomes very rapid, so that the branch of the 

 curve ascends nearly parallel to the axis of volume increase. 

 There w r e find that a slight increase in magnetization is 

 attended w r ith a large increase of volume. As the rate of 

 increase appears to be nearly constant it would be interesting 

 if we could push the field-strength still farther, to see whether 

 the volume-change ultimately attains an asymptotic value. 



The changes of volume and of length are shown in the 

 following tables : — 



Change of Volume. 



Nickel (1 ). 



Soft Iron (3). 



Steel (5). 



Wolfram Steel (8). 





Sv 





Sv 





Sv 





3v 



H. 



v' 



H. 



8 



v ' 



o-ioxio -7 



H. 



v ' 



H. 



19 



0-30X10 -7 



13 



0-09 X 10 ~ 7 



i 



0-08x10 



SO 



029 



11 



52 



12 



0-47 



42 



1-52 



90 



0-65 



18 



1-56 



33 



1-95 



93 



3-03 



218 



0-82 



167 



342 



192 



313 



216 



5-01 



282 



097 



443 



385 



376 



4-69 



442 



8-04 



517 



1-38 



691 



4-58 



586 



6-22 



692 



11-68 



877 



206 



958 



5-88 



792 



8-01 



1001 



1668 



1141 



2-44 



1115 



748 



1044 



1016 



; 1117 



18-96 



1547 



324 



1342 



947 



1376 



14-07 



: 1296 



22-75 



1740 



353 



1563 



11-45 



1646 



1720 



1704 



28-82 



2253 



412 



1 2089 



14-68 



2171 



22 20 



2153 



3262 



Kirchhoffs Constants k' and k". 

 Starting from the formulas 



~l I 3" " \l + 20j + 2(1 + 2(9) 2JE' 

 and 



which give the change of volume and of length of ferro- 

 magnetic ovoids in terms of Kirchhoff's constants k' and k", 



