PARAMAGNETIC AND DIAMAGNETIG FORCES. 24.9 
Cylinders of antimony were substituted for those of bis- 
muth. This metal is a better conductor of electricity, but 
less strongly diamugnetic than bismuth. If therefore the 
action referred to be due to induced currents we ought to 
have it greater in the case of antimony than with bismuth; 
but if it springs from a true diamaguetic polarity, the action 
of the bismuth ought to exceed that of the antimony. Ex- 
periment proves this to be the case. Hence the deflection 
produced by these metals is due to their diamagnetic, and 
not to their conductive capacity. Copper cylinders were 
next examined: here we have a metal which conducts elec- 
tricity fifty times better than bismuth, but its diamagnetic 
power is nearly null; if the effects be due to induced cur- 
rents we ought to have them here in an enormously exag- 
gerated degree, but no sensible deflection was produced by 
the two cylinders of copper. 
It has also been proposed by the opponents of diamagnetic 
polarity to coat fragments of bismuth with some insulating 
substance, so as to render the formation of induced cur- 
rents impossible, and to test the question with cylinders 
of these fragments. This requirement was also fulfilled. 
It is only necessary to reduce the bismuth to powder and 
expose it for a short time to the air to cause the particles 
to become so far oxidized as to render them perfectly 
insulating. The insulating power of the powder was 
exhibited experimentally; nevertheless, this powder, 
enclosed in glass tubes, exhibited an action scarcely less 
powerful than that of the massive bismuth cylinders. 
But the most rigid proof, a proof admitted to be con- 
clusive by those who have denied the antithesis of magnet- 
ism and diamagnetism, remains to be stated. Prisms of 
the same heavy glass as that with which the diamagnetic 
force was discovered, were substituted for the metallic 
cylinders, and their action upon the magnet was proved 
to be precisely the same in kind as that of the cylinders of 
bismuth. The inquiry was also extended to other 
insulators: to phosphorus, sulphur, niter, calcareous spar, 
statuary marble, with the same invariable result: each of 
these substances was proved to be polar, the disposition of 
the force being the same as that of bismuth and the 
reverse of that of iron. When a bar of iron is set erect, its 
lower end is known to be a north pole, and its upper end 
a south pole, in virtue of the earth's induction. A nwblo 
