MAGNETIZATION AND MAGNETIC CHANGE OF LENGTH. 23 



In Swedish iron and tungsten steel, cooling by liquid air 

 decreases the elongation of the metals ; the change in tungsten 

 steel is very small, but in Swedish iron, it is relatively large. In 

 nickel, the contraction is diminished by cooling to a field of 670 

 C.G.S. ; but it is increased in stronger fields. In cast cobalt, 

 the contraction is considerably increased, except in weak field, 

 where a slight decrease of contraction is observed. In annealed 

 cobalt, the contrary is the case ; the contraction is always dimin- 

 ished. 



With tungsten steel and nickel, the magnetic changes of length 

 before and after the cooling coincide with each other. But in 

 Swedish iron, the elongation after cooling becomes greater than 

 that before cooling. In cast cobalt, the magnetic contraction after 

 cooling slightly decreases, as compared with the elongation before 

 cooling ; but with annealed cobalt, the contrary is the case, except 

 in weak field. 



The above results for Swedish iron, nickel and annealed 

 cobalt agree with those obtained by us"^ with rods of these metals. 

 The change of elongation of tungsten steel in high fields does not 

 coincide with that of our former experiment. But the change 

 being very small, the discrepancy may be accounted for by taking 

 into consideration the demagnetizing force, with which our former 

 experiment was not concerned. 



(/) Length Change of Nickel Steels. 



The observed changes of length are given in Table VI and 

 in Fig. 4 a, b, c, d, e, f, g, h, i. 



*) K. Honda and S. Shimizu, loc. cit. 



