130 ON MAGNETISM. 



SECTION VIII. 



ON TEANSIENT INDUCED MAGNETISM IN SOFT IRON. 



56. Definition of Soft Iron, and criterion of the 

 magnetic difference between Soft Iron and Magnetized 

 Steel 



Under the term Soft Iron may be understood, either 

 Malleable Iron which has not been hammered or sub- 

 jected to any violence when cold, or Cast Iron. (We 

 shall in the next Section discuss the properties of 

 Malleable Iron when subjected in the cold state to 

 violence.) And the best practical criterion by which a 

 bar of Soft Iron is distinguished from a Steel Magnet is 

 this. We have found in Articles 16, 27, and other 

 places, that if, in the horizontal plane, a steel magnet is 

 applied end-on towards the center of a suspended hori- 

 zontal magnet, it tends to produce a deviation in the 

 position of the suspended magnet. Now if a bar of soft 

 iron be substituted for the steel magnet, the suspended 

 magnet will not be disturbed at all. In some positions, 

 if the suspended magnet be constrained by external 



