56 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXI.) 
each kind of matter were placed in the magnetic field both would become magnetic, 
and each would have its axis parallel to the resultant of magnetic force passing 
through it ; but the particle of magnetic matter would have its north and south poles 
opposite, or facing towards the contrary poles of the inducing magnet, whereas with 
the diamagnetic particles the reverse would be the case ; and hence would result 
approximation in the one substance, recession in the other. 
2430. Upon Ampere’s theory, this view would be equivalent to the supposition, that 
as currents are induced in iron and magnetics parallel to those existing in the inducing 
magnet or battery wire ; so in bismuth, heavy glass and diamagnetic bodies, the 
currents induced are in the contrary direction. This would make the currents in 
diamagnetics the same in direction as those which are induced in diamagnetic con- 
ductors at the commencement of the inducing current ; and those in magnetic bodies 
the same as those produced at the cessation of the same inducing current. No dif- 
ficulty would occur as respects non-conducting magnetic and diamagnetic sub- 
stances, because the hypothetical currents are supposed to exist not in the mass, but 
round the particles of the matter. 
2431. As far as experiment yet bears upon such a notion, we may observe, that the 
known inductive effects upon masses of magnetic and diamagnetic metals are the same. 
If a straight rod of iron be carried across magnetic lines of force, or if it, or a helix of 
iron rods or wire, be held near a magnet, as the power in it rises electric currents are 
induced, which move through the bars or helix in certain determinate directions 
(38. 1 14., &c.). If a bar or a helix of bismuth be employed under the same circum- 
stances the currents are again induced, and precisely in the same direction as in the 
iron, so that here no difference occurs in the direction of the induced current, and 
not very much in its force, nothing like so much indeed as between the current in- 
duced in either of these metals and a metal taken from near the neutral point (2399.). 
Still there is this difference remaining between the conditions of the experiment and 
the hypothetical case ; that in the former the induction is manifested by currents in 
the masses, whilst in the latter, i. e. in the special magnetic and diamagnetic effects, 
the currents, if they exist, are probably about the particles of the matter. 
2432. The magnetic relation of aeriform bodies is exceedingly remarkable. That 
oxygen or nitrogen gas should stand in a position intermediate between the magnetic 
and diamagnetic classes ; that it should occupy the place which no solid or liquid 
element can take ; that it should show no change in its relations by rarefaction to 
any possible degree, or even when the space it occupies passes into a vacuum ; that 
it should be the same magnetically with any other gas or vapour ; that it should 
not take its place at one end but in the very middle of the great series of bodies ; and 
that all gases or vapours should be alike, from the rarest state of hydrogen to the 
densest state of carbonic acid, sulphurous acid, or ether vapour, are points so striking, 
