12 ART. 10— K. HONDA & S. SHIMIZU. 



13, curves are drawn, one for each specimen, for the elongations at 

 such temperatures that each specimen produces the same elongation 

 in H = 500. They all run very close to each other. It is also to be 

 observed that the change of length at the critical temperature nearly 

 disappears, and even in cases, in which we actually observe it, the 

 amount of the change is a small fraction of that observed at ordinary 

 temperatures. 



In conclusion, let us give a short account of the permanent 

 change with regard to the magnetic change of length. Coolinçr the 

 specimens by liquid air generally produces no permanent effect on the 

 length change at ordinary temperature ; but heating it to a very 

 high temperature produces a considerable permanent change. As 

 seen from Fig. 14, the heating of annealed soft iron up to 746°C 

 does not sensibly affect the change of length at ordinary temperature. 

 Here the cross (x) denotes the points obtained after heating to 746°C. 

 In tungsten steel, the effect is very large, tending to reduce the 

 elongation in high fields (Fig. 15). In cast cobalt, the effect is still 

 greater, changing totally the course of the curve, as seen from Fig. 

 IG. If the specimen is once annealed at a high temperature, the 

 subsequent heating and cooling between the same range of tem- 

 peratures almost produce no effect on the change of length at ordinary 

 temperature. But if the upper range of temperature be further 

 increased, the change of length is slightly affected; This will be seen 

 from the example of annealed cobalt (Fig. 17). 



Iu the experiments at temperatures higher than 700°C, the 

 suspended weight was reduced to 1 or 0.4 kilogram, according to 

 circumstances. This was found necessary to avoid the gradual elonga- 

 tion of our specimens caused by the yielding at high temperatures. 



It is hoped that the present investigation may be completed by 

 studying the change of length in every stage of rising and falling 



