Effect of Stress on Magnetization. 97 



The effect o£ giving a maximum twist at once does not 

 materially differ from that of a graded twisting. 



(d) Magnetization under Constant Twist combined 

 with Tensions : (I, H) T , t. 



The effect of a constant twist on magnetization is com- 

 paratively great, especially in high fields. In 28*74 per cent. 

 Ni, the magnetization is slightly increased by a small twist, 

 but above a moderate twist it decreases. In 50*72 per cent. 

 Ni, the increase of magnetization by a small twist is not 

 appreciable, but the magnetization always decreases with 

 greater twist. The magnetization of 70*32 per cent. Ni is 

 also decreased by twisting, except in weak fields in which 

 a slight increase is observed. In all cases, the change of 

 magnetization decreases with increasing tension. 



In 28*74 per cent. Ni, curves (SI, H) r ,T (fig. 40 in dotted 

 lines) deduced from (I, H) r ,T show a somewhat different 

 aspect from those deduced from (SI, t) t .h, especially for a 

 small twist. For a small value of twist, SI is always positive 

 and has a faint maximum ; for a greater twist it is first 

 negative and afterward positive; and for a still greater 

 twist it is always negative, and, except in weak fields, it takes 

 a course parallel to the corresponding curve obtained from 

 the last experiment, but the former lies somewhat below the 

 latter. 



In 50*72 per cent. Ni, curves (81, H) r ,T (figs. 41 and 42 in 

 dotted lines) deduced from (I, H) r ,T have a quite different 

 aspect, i. e. SI is always negative. It rapidly decreases in 

 weak fields, and after passing through a negative maximum, 

 slopes away very slowly towards the axis of H with in- 

 creasing field. Tension reduces the decrease of magne- 

 tization. 



In 70*32 per cent. Ni, curves (SI, H) t ,t (figs. 43, 44, 45, and 

 46 dotted fines) deduced from (I, H) r ,T take a course similar 

 to those obtained from the last experiment, but the difference 

 is that in the former the positive maxima in weak fields are 

 considerably smaller, the points at which SI changes its sign 

 lie in a lower part of the field, and SI tends more slowly 

 to zero than in the latter. The effect of tension is to push 

 the points of intersection with the axis of H towards the 

 origin. 



For these allo}^s curves (SI, H) r>T as deduced from (I, H) r ,T 

 rather resemble the curves (Sic, H) r ,T obtained from the last 

 experiment. 



Phil. Mag. S. 6. Vol. 14. No. 79. July 1907. H 



