464. Trowbridge and Sheldon — Magnetism of Nickel, etc. 



o _ r 3 _£Ttan cp 

 m 



where 



r = distance from bar to magnetometer = 72-68 cm. 



H = earth's horizontal intensity = 0-1722. 



m = mass of the bar. 



q) = angular deflection 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. 



/Sfcm. f g. -\ sec. 



Pure Nickel 



18 X 2-7 X 0-65 





284-5 



1-23 



Ni + 3 <f W 



(( CC (C 





286-5 



10-60 



Ni + 4 f W 



CC U CC 





283-5 



10-40 



Tool Steel 



15 X 2-5 X 0-5 

 / Octagonal \ 



U3 X 1-oJ 





1595 



7-46 



Ni + 8 i W 





144-0 



5-25 



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

 GROUP II. 



Composition. 





Size in 



cms 





Mass in gms. 



£[cm 



,f g.-isec.- 1 ]. 



Pure Nickel 



18 



X 



1-8 



X 



1-6 



459 





1-05 



Ni + 1 fc W 



u 





CC 





CC 



455 





1-92 



Ni + 2 % W 



CC 





CC 





CC 



454 





1-70 



Ni + 3 f W 



c<. 





CC 





CC 



463 





1-75 



Ni + 6 f W 



CC 





CC 





CC 



465 





1-15 



The bars of both groups were, subsequent to the above ob- 

 servations, completely demagnetized, and then freshly magnet- 

 ized. New determinations gave the same results as before. 

 The demagnetization was accomplished by placing the bars in- 

 side 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 in this manner, they showed no appreciable 

 deflection when placed in position relative to the magnetometer. 



The results tabulated indicate that tungsten greatly increases 

 the magnetic moment of nickel, if the alloy be forged and 

 rolled, but on the other hand has but small influence if they be 

 simply cast. Furthermore, changes in the amount of tungsten 

 do not appear to cause corresponding changes in the magnetic 

 properties. 



To see whether the remarkable effect in bars 2 and 3, as 

 compared with bar 1, of Group I, was owing to some molecu- 



