48 



Prof. Nagaoka and K. 



Honda on Magnetostriction 



demagnetizing factor N of the ovoids examined in the present 

 experiments, a, semi-minor axis of ovoid ; c, semi-axis of 

 rotation of ovoid ; v, volume; p, density, determined by 

 hydrostatic balance. 



The difference in the volume of ovoids is to be attributed 

 to the slight deviation from exact geometrical shape. As most 

 specimens of cobalt contain more or less quantities of nickel, 

 the cast and annealed samples were chemically analysed 

 by Mr. Y. Suzuki, student in chemistry, with the following 

 result:— Cast cobalt, Co 93'36, M 5*05, Fe 1-20, C 1*38, 

 Si 0-39, Cu 0-17, Mn 0"12 ; Annealed cobalt, Co 92'74, 

 Ni 4-07, Fe 1-07, C 1-64, Si 0'28, Cu 0-15, Mn 004. 



The magnetization was determined magnetometrically * as 

 given in the following table : — 



Cast Steel. 



Nickel. 



Cobalt (cast). 



0-8 



3- 



44 



$■ 



3- 



27 



3- 



30 



10 



14 



13 



135 



2-7 



76 



56 



83 



1-6 



319 



5-5 



139 



147 



274 



3*1 



633 



7-8 



198 



194 



340 



7-4 



878 



11-7 



252 



300 



467 



23-0 



1122 



18-2 



314 



447 



572 



140 



1433 



333 



377 



89-8 



778 



302 



1555 



599 



426 



256 



984 



5J1 



1627 



116 



459 



474 



1080 



597 



1644 



482 



484 



643 



1119 



672 



1648 



796 



486 



720 



1136 



Cobalt 



Nickel-Steel 



Nickel-Steel 



Nickel-Steel 



(annealed). 



(46 p. cent. Ni). 



(36 p. cent.). 



(29 p. cent.). 



3-6 



3- 



4 



$. 



3- 



$■ 



3- 



1-2 



3- 



24 



0-9 



36 



17 



38 



134 



22 



2-7 



102 



4-8 



134 



26 



81 



224 



38 



4 2 



241 



9-4 



352 



64 



139 



426 



90 



6-2 



465 



1 146 



524 



13-3 



188 



775 



188 



169 



926 



' 30-4 



720 



247 



224 



195 



367 



35-5 



1108 



: 85-5 



900 



462 



243 



281 



439 



120 



1274 



150 



934 



68-8 



249 



364 



527 



231 



1308 



262 



953 



140 



256 



461 



568 



380 



1323 



i 367 



962 



325 



264 



617 



633 



557 



1333 



1 510 



971 



575 



273 



788 



699 



778 



1345 



i 818 



992 



893 



280 



* The magnetizing coil had the following constants ; — Length = 30 cm. 

 diam. of the core = 3*2 cm., 4ttw= 379-7, resistance =0-63 ohm. The 

 ovoid was placed axially, so that the extremities of the axis were at 5 cms, 

 distance from the ends of the coil, thus insuring the uniformity of the field. 



