produced by Magnetization* 



467 



lims. ; weight, 5*17 grms. ; specific gravity, 6*54 ; and thickness, 

 1*24 millim. 



In none of these sets of experiments is there any such equali- 

 zation of the positive and negative magnetisms as is effected by 

 powerful currents in the case of steel bars, although, in fact, 

 very powerful currents were applied to some of these electrolytic 

 magnets. The currents employed in 9, 12, and 13 were excited 

 by a six-celled Grove's battery. Divisions 7, 8, and 9 exhibit 

 the same irregularity as occurred with respect to temporary 

 magnetism ; the values of the negative magnetism rose slightly 

 instead of falling. 



Plates 7 and 8 were very thin, and therefore very perfectly 

 magnetized. The current which acted on 10 was very weak. If 

 the entire magnet be again supposed to be made up of a num- 

 ber of molecular magnets, whose axes are at first, for the most 

 part, parallel to each other, and in the same direction as the poles 

 of the entire magnet, then every force which tends to reverse the 

 polarity of the entire magnet will have to turn these axes out of 

 their original positions. A weak current only effects this by 

 repeated efforts (as in experiment 1 0) ; and any force succeeds in 

 it with more difficulty in proportion as the angle at which it 

 acts on the axes is more acute — that is to say, the more nearly 

 the axes of the molecular magnets are parallel to the geometrical 

 axis of the entire magnet (as in experiments 7 and 8). If, how- 

 ever, the current is strong and the axes of the particles deviate 

 far from parallelism, as is the case in thick plates, then the cur- 

 rent at once succeeds in producing a maximum effect. 



Repeated changes of polarity must, however, in general increase 

 the mobility of the particles, and therefore diminish their per- 

 manent magnetism, that is to say, their tendency to assume a 

 particular position on the cessation of the magnetizing current, 

 whence the general approximation of the positive and negative 

 magnetisms to equality. It is clear that all these changes must 



