2 AßT. 11 -H. XAGAOKA & K. HONDA. 



ing the magnetostriction of these valuable alloys appears from the 

 following words of Mons. L. Dumas in his report on researches con- 

 cerning nickel steels. 



"M. Guillaume, d'autre part, a fait remarquer que notre hypothèse 

 ne fournit aucune base pour l'interprétation des phénomènes de 

 magnetostriction, signalés par Mess. Xagaoka et Honda comme constatés 

 sur des aciers au nickel qui ont été mis à leur disposition par Imphy. 

 Tel est l'état actuel de cette intéressante question.'' We hope that the 

 present experiment will give some clue to a theory, which will explain 

 not only the thermal, electrical, and magnetic behaviour of the metal, 

 but also various metallurgical and mechanical properties. 



Metlwd of experiment. — The nickel steel rods were all turned 

 into ovoids (2a = 20 cm., 2b=l cm.), and placed axially in a coil (30 

 cm. long, 0.6 Ohm resistance, 4-m= 379.7). The magnetization was 

 determined by means of a magnetometer, the effect of the coil being 

 compensated by means of another coil of the same strength placed 

 symmetrically on the other side of the magnetometer. The change 

 of length was measured by means of an apparatus described in the 

 Philosophical Magazine, February, 189-1, and in this journal Vol. 

 IG. Art. 8. The ovoids were sealed in dilatometer, and the change 

 of volume measured by the displacement of the capillary meniscus« 

 In all these experiments, the utmost care was taken to eliminate the 

 effect of heating by waterjacketing the coil, and by observing the 

 displacement, a few seconds after making the magnetizing current. 

 The ovoids were demagnetized by the method of reversals of gradually 

 decreasing currents before each observation. 



MtKjnctizatiun of nickel steels. — From experiments made with 

 eight different specimens of nickel steels, „varying from 26.2 to 44 

 percent of nickel, Dumont u found a gradual increase of susceptibility 



1) Duuiont, Comptes Keudus, p. 741, torn. 76, 1898. 



