100 II. NAGAOKA. 



reversed polarity, and the curve which was double looped transforms 

 into a single looped curve. 



Now the question naturally suggests itself, can this curious 

 phenomenon of the reversal of polarity as well as other remarkable 

 characteristics in the magnetization of nickel be still observed in 

 wires taken from different sources, and also for different angles of 

 twist? The objects of the experiments now tobe described are to 

 fill in these gaps, and also to extend the investigation to the case 

 of iron. 



The method of procedure was exactly the same as in the former 

 experiments. The intensity of magnetization was measured by the 

 direct magnetometric method from the amounts of deflection of a 

 magnetometer mirror. The wire was placed vertically within a 

 solenoidal coil, and its upper end was magnetic east of the magneto- 

 meter mirror. A constant magnetic field was maintained within the 

 solenoid ; and as the wire was subjected to the given cyclic twisting, 

 the deflections on the magnetometer scale were noted. The twist 

 was applied by means of the twisting apparatus described in the 

 former paper. The effects were examined for two specimens of nickel 

 wire obtained from different manufacturers. They were of different 

 diameters, being 0"86 nun. and 1 mm. thick respectively. The latter 

 was the one used in earlier experiments. Each wire studied was first 

 annealed by gently passing it over the flame of a spirit lamp three or 

 four times. 



As the object of the investigation was merely to examine the 

 changes of magnetization, T have not thought if necessary to reduce 

 the observed readings to absolute units; and consequently the num- 

 bers given are simply in terms of the scale unit. The reversal of 

 polarity and other accompanying changes are so complicated that l 

 have examined only a few particular cases, and most of the experi- 



