SUPPOSED POLARITY OF DIAMAGNETIC BODIES. 
185 
of that force, which, when it is not there, exists in the plane occupied by the bismuth. 
Hence, in passing through 90°, the diamagnetic is urged by a mucli greater difference 
of intensity of force when the iron is present than when it is away ; and hence, pro- 
bably, the whole additional result. The effect is like many others which I have re- 
ferred to in magnecrystallic action (2487-2497.), and does not, I think, add anything 
to the experimental proof of diamagnetic polarity. 
2693. Finally, I am obliged to say that I can find no experimental evidence to 
support the hypothetical view of diamagnetic polarity (2640.), either in my own 
experiments, or in the repetition of those of Weber, Reich, or others I do not 
say that such a polarity does not exist ; and I should think it possible that Weber, 
by far more delicate apparatus than mine, had obtained a trace of it, were it not that 
then also he would have certainly met with the far more powerful effects produced 
by copper, gold, silver, and the better conducting diamagnetics. If bismuth should be 
found to give any effect, it must be checked and distinguished by reference to the 
position of the commutator, division of the mass by pulverization, influence of time, 
&c. It appears to me also, that, as the magnetic polarity conferred by iron or nickel 
in very small quantity, and in unfavourable states, is far more readily indicated by 
its effect on an astatic needle, or by pointing between the poles of a strong horseshoe 
magnet, than by any such arrangement as mine or Weber’s or Reich’s, so diamag- 
netic polarity would be much more easily distinguished in the same way, and that 
no indication of that polarity has as yet reached to the force and value of those 
already given by Brugmann and myself. 
2694. So, at present, the actions represented or typified by iron, by copper and 
by bismuth, remain distinct ; and their relations are only in part made known to us. 
It cannot be doubted that a larger and simpler law of action than any we are yet 
acquainted with, will hereafter be discovered, which shall include all these actions at 
once ; and the beauty of Weber’s suggestion in this respect was the chief induce- 
ment to me to endeavour to establish it. 
2695. Though from the considerations above expressed (2693.) I had little hopes 
of any useful results, yet I thought it right to submit certain magnecrystallic cores 
to the action of the apparatus. One core was a large group of symmetrically 
disposed crystals of bismuth (2457.) ; another a very large crystal of red ferroprus- 
siate of potassa ; a third a crystal of calcareous spar; and a fourth and fifth large 
crystals of protosulphate of iron. These were formed into cylinders of which the 
first and fourth had the magnecrystallic axes (2479.) parallel to the axis of the 
cylinder, and the second, third and fifth, had the equatorial direction of force (2594. 
2595. 2596.) parallel to the axis of the cylinder. None of them gave any effect at 
the galvanometer, except the fourth and fifth, and these were alike in their results, 
and were dependent for them on their ordinary magnetic property. 
2696. Some of the expressions I have used may seem to imply, that, when employing 
the copper and other cores, I imagine that currents are first induced in them by the 
2 B 
MDCCCL 
