52 Prof. Nagaoka and K. Honda on Magnetostriction 



(d) Reversible Nickel-Steels. 



Through the kindness of Messrs. Ch. Ed. Guillaume and 

 Dumas, who supplied us with the different samples of reversible 

 nickel-steels, manufactured by Commentry-Fourchambault 

 at Deeazeville, we were enabled to examine the magneto- 

 striction of reversible nickel-steels in its various aspects. 



The samples to be tested were either turned into ovoids of 

 the same dimensions as for the other metals, or used in the 

 form of wires. These two sets of metal of different shape 

 do not show serious discrepancies in the observed results, 

 which are given below for specimens containing different 

 percentages of nickel, either in the form of ovoids or wires. 

 It is to be remarked that the annealing of nickel-steel was 

 conducted in a glass tube, through which hydrogen was kept 

 in constant circulation, and heated to 500° C. upwards for 

 more than three hours. 



The curves of the length-change are plotted in fig. 3. 



All the nickel-steels indicate increase of length in fields up 

 to about § = 2000. The character of the change for 46 per 

 cent. Ni resembles that for nickel with opposite sign, inas- 

 much as the curve of elongation in the former has great 

 resemblance to that of contraction in the latter, and is similar 

 to that for the intensity of magnetization. The elongation in 

 very weak fields takes place slowly, but in fields of about 30 

 units the rate of change is most rapid, and soon reaches an 

 inflexion-point, whence to increase in length very slowly and 

 finally in an asymptotic manner. 



Fig. 3. 

 si 



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c 

 6 '' 



r, ^--j^-~ 









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ij 





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- = - c 



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'a" , 



"'b* 



















i h' / 



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c. 



















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200 400 600 800 1000 l?00 1400 1600 1800 1=000 £ 



a — nickel-steel ovoid (46 p. c. Ni). j a ' = nickel-steel wire (46 p. c. Ni) annealed. 

 b— „ „ „ (36p.c. Ni). \a''= „ „ „ ,, unauuealed. 



c= „ „ „ (29 p. c. Ni). \b'= „ „ „ (35 p. c.Ni) annealed. 



\b"= „ „ „ ,> unannealed. 



With the 36 per cent. Ni we observe similar features in 

 the curve of elongation. The inflexion-point lies in higher 



