1891.] on the Molecular Process in Magnetic Induction. 



395 



group. But if we carry the process far enough to have unstable 

 deflections, the effects of these persist when the force is removed, 

 for the magnets then retain the new grouping into which they have 

 fallen (Fig. 10). And again, the quasi- elastic deflections which go 

 on during the third, stage do not add to the residual magnetism. 



Notice, further, what happeus to the group if after applying a 

 magnetic force in one direction and removing it, I begin to apply 

 force in the opposite direction. At first there is little reduction of 

 the residual polarity till a stage is reached when instability begins, 



Fig. 12. 



Cyclic reversal of magnetisation in (A a) annealed iron wire, (b b) the same piece 



hardened by stretching. 



and then reversal occurs with a rush. We thus find a close imitation 

 of all the features that are actually observed when iron or any of the 

 other magnetic metals is carried through a cyclic magnetising process 

 (Fig. 12). The effect of any such process is to form a loop in the 

 curve which expresses the relation of the magnetism to the mag- 

 netising force. The changes of magnetism always lag behind the 



