the Intrinsic Field of a Magnet. 



403 



temperature, especially prominent in nickel, which can be 

 brought about by the application of an alternating magnetic 

 field, which may be used as a test of the magnitude of the 

 magnetic intrinsic field. If a nickel wire is subjected to an 

 alternating field, then its ferro-magnetism is lost at a tempe- 

 rature 50° to 100° C. lower than its normal critical tempera- 

 ture. Curves illustrating this are shown in the upper diagram 

 ofjfig. 1, which is taken from a former paper published in 



Fio-. 1. 



flr>HvsTerefi\ /sdaf l 



this Journal *. Here it is seen that the ferro- magnetic 

 intensity (I), and therefore the intrinsic magnetic field 

 (VI 2 ), virtually vanish under the action of an alternating 

 field at a temperature of about 560° A. instead of 660° A.; 

 and therefore it is to be expected that the other properties 

 named above, which must be influenced by the withdrawal 

 -of such a large field, will change in some measure at this 



* Phil. Mag. vol. xxvii. p. 367. 



2 D2 



