34 K. TSURUTA. 



ing and unloading gone through once more, there is brought forth 

 the form of the curve which is of the type given by Dr. Cohn. A 

 farther extension of the range of cyclic change by 2 kilos., making the 

 greatest load 8 kilos., wrought no change in the form of the curve ; it 

 had only the effect of prolonging the branches towards the positive 

 region of E. M. F. 



Another extension of the range up to 10 kilos, had the same 

 effect, and here the two cyclic curves, the dotted and the full, are 

 almost coincident with each other, this in the preceding stages not 

 being the case to such an extent. With 10 kilos, the wire was loaded 

 to the utmost, for when I added only 0*2 kilos., I observed a large- 

 strain which threatened to break down the wire. So Ptook away the 

 added load and obtained the reading corresponding to 10 kilos. 

 This is the reason why the dotted curve in Fig. 5 is not here connect- 

 ed. This permanent drawing of the wire wrought a great change in 

 the variation of E. M. F. : for when the wire was unloaded down to 

 5 kilos., further unloading resulted in bringing the representative 

 point back towards the positive side of the axis of load and finally up 

 to the initial position. 



The cycle (0 — 10 — 0) gone through immediately after this great 

 change is shown in Fig. 6., PI. I. It is exactly of the type given by 

 Prof. Ewing. Experiments with other pieces of wire showed that 

 once the change had set in, the cyclic curves obtained after the lapse 

 of hours and days were all exactly of the above type. 



§ 9. The above experiment made, as it was, upon a single 

 sample of soft iron, must be regarded as a particular example. In 

 fact, the curves obtained, even with pieces of wire cut from the same 

 bundle, showed some differences in details. So far, however, as my 

 experiments go, all samples of soft iron well annealed, when tested, 

 agree in exhibiting a considerable reduction of E. M. F. on being 



