Intelligence and Miscellaneous Articles. 137 



amperes was then sent through the coil for one minute, and the 

 circuit then broken and the bars removed. 



For the determination of the magnetic moment, use was made 

 of a re fleeting-magnetometer, and deflexions were observed with a 

 telescope and scale at a scale-distance of 100 centim. Measure- 

 ments of the horizontal intensity, H, of the earth's magnetism 

 were first made. The results from these determinations by means 

 of the first and second Gauss arrangements were, respectively, 

 H=0*1724 Centim. G. S. 

 - H= 0-1720 

 The freshly magnetized bars were then placed in the second G-uass 

 position relative to the magnetometer, and the angular deflexion 

 determined. The specific magnetism, S, was then calculated by 

 the formula 



o _ r 3 H tan <j> 

 m 

 where 



r = distance from bar to magnetometer = 72*68 centim. ; 



H = earth's horizontal intensity = 0*1722; 



m = mass of the bar ; 



= angular deflexion of magnetometer. 



Results. 

 The mean results of two sets of observations on Group I., and 

 also upon a similar bar of soft tool steel, are given in the following 

 table : — 



Group I. 



Composition. 



Size in cms. Mass in grams. 



StOm.ta.-lSec- 1 ]. 



Pure Nickel 



18x2-7x0-65 284-5 



1*23 



m + 3 p. c. w 



„ „ „ 286-5 



10*60 



Ni + 4 p. c. W 



„ „ „ 283*5 



10*40 



Tool Steel 



15x2-5x0-5 159-5 



7*46 



(Octagonal "\ 

 13 x 1-5 J 144-0 5'25 



Group II., of cast bars, gave the following results : — 



Group II. 



Composition. Size in cms. 3 



Pure Nickel 18 x 1*8 x 1-6 



M+lp.c.W „ „ „ 

 Ni + 2p.c.W „ „ „ 

 Ni + 3p.c.W „ „ „ 

 Ni + 6p.c.W „ „ „ 



The bars of both groups were, 

 vations, completely demagnetized, 



New determinations gave the same results as before. The de- 

 magnetization was accomplished by placing the bars inside two 

 coils,, which were traversed by currents from an alternating 

 dynamo. The coils were then slowly drawn apart, and the bars 

 maintained at a position central between them. After treatment 



Phil. Mag. S. 5. Vol. 29. No. 176. Jan. 1890. L 



ass in grams. 



S[Cm 



A G-.-t Sec.- 1 ]. 



459 





1*05 



455 





1*92 



454 





1*70 



463 





1*75 



465 





1*15 



subsequent 



to the above obser- 



and then freshly 



magnetized. 



