670 EXPERIMENTAL INVESTIGATION OF THE 
68. The Mono-magnetics at present known 
are but few in number, iron being the grand type. 
Next to iron is nickel. Cobalt is also a mono- 
magnetic body, and, at present, completes the list 
of this class of magnetics. 
69. In the Suno-magnetic class I place alloys 
of copper and silver, copper and gold, and cop- 
per and zinc; and, although these three are the 
only ones with which we are yet acquainted, I 
have no doubt that many more alloys will soon 
find a place among suno-magnetics. 
70. The Kato-magnetics are very numerous, 
as this class includes all bodies which, by combi- 
nation, impair the magnetism of other bodies. 
Amongst the metallic Kato-magnetics, zinc is the 
most powerful hitherto ascertained. Next to zinc 
is antimony. Then lead and tin. Arsenic, probably, 
stands very high in this class, but I have had no 
opportunity of ascertaining its proper place. The 
non-metallic Kato-magnetics are sulphur, oxygen, 
cyanogen, chlorine, carbon, and the generality 
of those bodies which combine with the metals. 
71. In proposing this classification of magnetics 
