30 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXVI.) 
a greater conducting power, the latter will tend to draw up towards the place of 
greatest force, displacing the former. Such at least is the case with bodies that are 
freely magnetic, as iron, nickel, cobalt and their combinations (2357. 2363. 2367- &c.), 
and such a result is in analogy with the phenomena produced by electric induction. 
If a portion of still higher conducting power be brought into play, it will approach 
the axial line and displace that which had just gone there; so that a body having a 
certain amount of conducting power, will appear as if attracted in a medium of weaker 
power, and as if repelled in a medium of stronger power by this differential kind of 
action (2367. 2414.). 
2799. At the same time that this idea of conduction will thus account for the place 
which a given substance would take up, as of oxygen in the axial line if in nitrogen, 
or of nitrogen at a distance if in oxygen, it also harmonizes with the fact, that there 
are no currents induced in a single gas occupying the magnetic field (2754.), for any 
one particle can then conduct as well as any other, and therefore will keep its place; 
and it also agrees, I think, with the unchangeability of volume (2750.). 
2800. In reference to the latter point, we have to consider that the force which 
urges such a body as oxygen towards the middle of the field, is not a central force 
like gravitation, or the mutual attraction of a set of particles for each other ; but an 
axial force, which, being very different in character in the direction of the axis and of 
the radii, may, and must produce its effect in a very different manner to a purely 
central force. That these differences exist, is manifest by the action of transparent 
bodies, when in the magnetic field, upon a ray of light; and also by the ordinary 
action of magnetic bodies : and hence, perhaps, the reason, that when oxygen is 
drawn into the middle of the field, in consequence of its conducting power, still its 
particles are not compressed together (2721.) by a force that otherwise would seem 
equal to that effect (2766.). 
2801. So when two separate portions of oxygen or nitrogen are in the magnetic 
field, the one passes inwards and the other outwards, without any contraction or ex- 
pansion of their relative volumes; and the result is differential, the two bodies being 
in relation to and dependence on each other, by being simultaneously related to the 
lines of magnetic force which pass conjointly through them both, or through them, 
and the medium in which they are conjointly immersed. 
2802. I have already said, in reference to the transference onwards of magnetic 
force (2787.), that pure space or a vacuum permits that transference, independent of 
any function that can be considered as of the same nature as the conducting power 
of matter ; and in a manner more analogous to that in which the lines of gravitating 
force, or of static electric force, pass across mere space. Then as respects those 
bodies which, like oxygen, facilitate the transmission of this power more or less, they 
class together as magnetic or paramagnetic substances (2790.) ; and those bodies, 
which, like olefiant gas or phosphorus, give more or less obstruction, maybe arranged 
together as the diamagnetic class. Perhaps it is not correct to express both these 
