468 On the Molecular Changes produced by Magnetization. 



also exhibit themselves in values of the temporary magnetism. 

 Steel magnets can only behave in the same way as these elec- 

 trolytic plates when the force by which they were originally 

 magnetized was greater than that subsequently employed to 

 change their polarity. If, on the other hand, the latter force is 

 the greater, steel bars behave, as Wiedemann has shown, as if 

 freshly magnetized. 



For the sake of comparison, I made some experiments in 

 which the polarity of an electrolytic magnet was repeatedly re- 

 versed by rubbing with another magnet. The results were not 

 in this case so uniform, but nevertheless they clearly proved 

 that an electrolytic magnet, even when rubbed with the pole of 

 a powerful permanent magnet, behaves precisely in the same 

 way as a steel bar when rubbed with the pole of a magnet less 

 powerful than that by which it had been originally magnetized. 

 Even thickish plates were generally weakened by the first stroke, 

 which magnetized them in the direction of their original mag- 

 netism ; and after repeated changes they exhibited an increase in 

 the amount of negative magnetism, precisely as in the experi- 

 ments with magnetizing currents. 



Plate 14. Length, 48 millims. ; breadth, 30 millims. ; weight, 

 16*42 grms. ; specific gravity, 6*12; consequent thickness, 17 

 millim. 



Plate 15. Length 65 millims. ; breadth, 10 millims. 



This manner of conducting the experiment admits, however, 

 of very little precision, partly because it is impossible entirely 

 to avoid shaking the plate, partly because it is uncertain whether 

 the axis of the magnet which is being rubbed remains always 

 the same. 



The hypothesis of a separation of magnetic fluids consequent 

 on magetization is altogether insufficient to explain the foregoing 

 results. According to that hypothesis, it is impossible to con- 

 ceive that when an iron bar has been deprived of its magnetism, 

 it should behave differently when exposed to those influences 

 which tend to magnetize it again in the same way as at first, from 



