CONSTANCY OF MAGNECRYSTALLIC FORCE IN DIFFERING MEDIA. 
165 
the use of a more paramagnetic or better conducting medium should have a con- 
trary effect and make the magnecrystal appear less affected ; for the transmission of 
power would be increased (proportionally) everywhere else, more than through it. 
On the contrary, the use of a more diamagnetic medium would have the reverse 
effect, and the transmission of force decreasing everywhere else more than through 
the crystal, would make the latter appear to increase in its peculiar condition of force. 
I am assuming that the magnet is unchangeable in power, and therefore must exert 
the like external force in every case ; and after all, I conclude that these effects would 
be so small, as not to be observable except by the use of media differing far more 
from each other than those we at present possess. For my own part, I feel, even now, 
that the hypothesis of magnetic fluids cannot exist in the presence of conjoint para- 
tnagnetic and diamagnetic phenomena; but considerations such as those above, may 
be able to do good service in arranging hypotheses in their right places and giving 
them their true value. 
3384. The aptitude of a magnecrystal, when in the magnetic field, to assume a 
maximum conductive state in a given direction, makes it similar in action to a per- 
manently magnetized sphere ; and therefore, however diamagnetic it may be, and 
however slight its magnecrystallic condition, still it will set in a definite direction, 
i. e. with its chief magnecrystallic axis* parallel to the magnetic axis of the field, 
even if it could be surrounded by a fluid medium having a paramagnetic condition 
equal to that of iron. And here I wish to correct an expression which has been 
allowed in aformer series of these Researches (3158.), where it is said, that ‘^an ordi- 
nary magnetic needle cannot show polarity in a field of equal force.” It cannot of 
course exist in association with a field of equal force, for it would itself destroy the 
eqaalityof the force, unless the medium around it were iron as high in paramagnetic 
power as itself; but even in such a case it would show polarity when deflected, for its 
magnetic axis would correspond in quality with a chief magnecrystallic axis, and it 
would always set or point in the accordant direction, i. e. axially in the magnetic field. 
3385. Magnecrystals may be employed in experiments to measure magnetic force 
just as needles are, but in some points of view they are philosophically more accurate. 
A magnecrystal is equal in quality in all its parts; it appears to take up precisely 
the same state under the same inductive force and to have no coercitive or retentive 
faculty; whereas the force of a needle changes easily under inductive action, and 
when that action ceases the return towards its former condition is uncertain. It is 
also independent of the surrounding medium. Hence it may, in some cases, be 
found to supply a more true and certain standard of force, in the amount of tension 
required for its deflection. 
3386. That magnecrystals are attracted or repelled wdth different degrees of force 
in different directions, has been long ago established by myself (2841.) and others. 
* Thomson on Magnecrystallic Axis, Philosophical Magazine, 1851, vol. i. p. 177. 
MDCCCLVI. 
Z 
