CHAP, v.] ELECTRICITY AND MAGNETISM. 303 



suspended in a more highly magnetic fluid. A small 

 glass tube filled with a weak solution of ferric chloride, 

 when suspended in air between the poles of an electro- 

 magnet points axially, or is paramagnetic ; but if it be 

 surrounded by a stronger (and therefore more magnetic) 

 solution of the same substance, it points equatorially, and 

 is apparently repelled like diamagnetic bodies. All that 

 the equatorial pointing of a body proves then is, that it is 

 less magnetic than the medium that fills the surrounding 

 space. A balloon, though it possesses mass and weight, 

 rises through the air in obedience to the law of gravity, 

 because the medium surrounding it is more attracted 

 than it is. But it is found that diamagnetic repulsion 

 takes place even in a vacuum : hence it would appear 

 that space itself 1 is more magnetic than the substances 

 classed as diamagnetic. 



342. Diamagnetic Polarity. At one time Faraday 

 thought that diamagnetic repulsion could be explained 

 on the supposition that there existed a " diamagnetic 

 polarity " the reverse of the ordinary magnetic polarity. 

 According to this view, which, however, Faraday him- 

 self quite abandoned, a magnet, when its N. pole is pre- 

 sented to the end of a bar of bismuth, induces in that 

 end a N. pole (the reverse of what it would induce in a 

 bar of iron or other magnetic metal), and therefore repels 

 it. Weber adopted this view, and Tyndall warmly 

 advocated it, especially after discovering that the repell- 

 ing diamagnetic force varies as the square of the 

 magnetic power employed, a law which is the counter- 

 part of the law (Art. 330) of attraction due to induction. 

 Many experiments have been made to establish this 

 view ; and some have even imagined that when a 

 diamagnetic bar lies equatorially across a field of force, 

 its east and west poles possess different properties. The 

 experiments named in the preceding paragraph suggest, 

 however, an explanation less difficult to reconcile with 



1 Or. possibly, the " aether '' filling all space. 



