236 NOTICES OF THE MEETINGS [Jan, 21, 
The cause of this variation in the ratio of the substances one to 
another, if it be finally proved, has still to be searched out. It 
may depend in some manner upon the forms of the lines of mag- 
netic force, which are different at different distances; or not upon 
the forms of the lines but the amount of power at the different 
distances ; or not upon the mere amount, but on the circumstance 
that in every case the body submitted to experiment has lines of 
different degrees of force passing through different parts of it, 
(for however different the magnetic or diamagnetic conditions of a 
body and the fluid surrounding it, they would not move at all in 
relation to each other in a field of equal force) : but whatever be the 
cause, it will be a concomitant of magnetic actions; and therefore 
ought to be included in the results of any law by which it is supposed 
that these actions are governed. 
It has not yet been noticed that these general results appear to be 
in direct opposition to those of Pliicker, who finds that diamagnetic 
power increases more rapidly than magnetic power with increase of 
force. But such a circumstance, if both conclusions be accordant 
with facts, only shews that we have yet a great deal to learn about 
the physical nature of magnetic force ; and we must not shut our eyes 
to the first feeble glimpses of these effects, because they are incon- 
sistent on both sides with our assumed laws of action ; but rather seize 
them, as hoping that they will give us the key to the truth of 
nature. Bodies, when subject to the power of the magnet appear 
to acquire a new physical state, which varies with the distance or the 
power of the magnet. Each body may have its own rate of increase 
and decrease ; and that may be such as to connect the extreme effect 
of Pliicker, amongst paramagnetic bodies on the one hand, and the 
extreme effects amongst diamagnetic bodies now described, on the 
other; and when we understand all this rightly, we may see the 
apparent contradiction become harmony, though it may not conform 
to the law of the inverse square of the distance as we now try to 
apply it. 
Pliicker has already said, because of his observations regarding 
paramagnetic and diamagnetic force, that no correct list of magnetic 
substances can be given. The same consequence follows, though in 
a different direction from what has now been stated, and hence the 
reservation before made (p. 232). Still the former table is given as an 
approximation, and it may be useful fora time. Before leaving his 
first account of recent experimental researches, it may be as well to 
state that they are felt to be imperfect and may perhaps even be 
overturned ; but, that as such a result is not greatly anticipated, it 
was thought well to present them to the Members of the Royal 
Institution and the scientific world, if peradventure they might excite 
criticism and experimental examination, and so aid in advancing the 
cause of physical science. 
On a former occasion * the existence of physical lines of force in 
* Proceedings of the Royal Institution, p. 216. 
