PEIKCE. — ANOMALOUS MAGNETIZATION OP IRON AND STEEL. 641 



it frequently happens that the sign of the residual moment is opposite 

 to that while exposed to the field. Figure 3 shows a typical case of a 

 certain kind, that of a solid piece of carefully annealed " Cold Rolled 

 Shafting " 8 centimeters long and 3 centimeters in diameter. The " de- 

 magnetizing effect of the ends " in a rod of these dimensions is, of 



Figure 3. The ordinates of these curves show the magnetic condition of 

 a soft cylinder of mild steel 8 centimeters long and 3 centimeters in diameter, 

 when the exciting current had been taken off — gradually, in the case of the 

 full curve — suddenly in the case of the curve OPQ in which the negative 

 ordinates indicate anomalous magnetization. 



course, very great, and the residual moment in this instance was for 

 many currents less than one per cent of the moment originally induced 

 in the metal. The long, uniformly- wound solenoid used for this ex- 

 periment had a number (n) of turns per centimeter of its length such 

 as to make Avn/lO almost exactly 25. In the figure, which represents 

 a large number of observations, the horizontal unit corresponds to a 

 field of 100 gausses if the iron were taken out of the solenoid. The 

 actual field to which any portion of the rod was exposed for any value 

 of the exciting current was of course difficult to determine. When 

 the exciting current was suddenly broken a small spark appeared, and 

 if the strength of the current was not greater than about 30 amperes, 

 the remanent moment was of reversed sign. 



VOL. XLVII. — 41 



