MAGNETIC CONDUCTION — DISTINCTIONS. 
39 
conductor, subject to the same lines of force, still with a great difference ; for as the 
internal particles of iron become in a degree each a system producing magnetism, 
so their polarity is correlated and combined together into a polar whole, which, being 
infinitely more intense, may also be very different in the disposition of its force in 
different parts, to that equivalent to polarity, which a mere conductor possesses. 
2834. It appears to me also as very probable, that when iron, nickel and cobalt? 
are heated up to the respective temperatures at which they lose their wonderful 
degree of power (2347.) and retain only so small a portion of it as to require the 
most sensible test to make it manifest (2343.), they then have passed into the condi- 
tion of paramagnetic conductors, have lost all ability to acquire that state of internal 
polarity they could assume as magnets, and now have no other polarity than that 
which belongs to them as masses of paramagnetic matter (2819.). It is also pro- 
bable that in many states of combination these metals may take up the mere con- 
ducting state ; for instance, that whilst in the protoxide, iron may constitute a mag- 
net, in the peroxide it is only a conductor ; and in this respect it is not a little 
curious to find oxygen, which as a gas is a paramagnetic body (2782.), reducing iron 
down to, and indeed far below its own condition, weight for weight. In their 
various salts also and solutions, these metals may, in conjunction with the combined 
matter, be acting only as conductors. 
2835. Perhaps I ought not to have called the condition of concentration or expan- 
sion of the lines of magnetic force in the bodies acting as conductors, a polarity; 
inasmuch as true magnetic polarity depends essentially and entirely on the direction 
of the line of force, and not on any mere compression or divergence of these lines. 
I have done so only that I might point with the more facility to facts and views that 
have heretofore been associated with some supposed polarity in the bodies which, 
whether paramagnetic or diamagnetic, I have been considering as mere conductors, 
and I hope that no mistake of my meaning will arise in consequence. I have already 
asked for such liberty in the use of phrases (lines of force, conducting power, &c.) 
(2149. 2797 .) as may, for the time, set me free from the bondage of preconceived 
notions ; these are, for that very reason, exceedingly useful, provided they are for the 
time sufficiently restricted in their meaning, and do not admit of any hurtful loose- 
ness or inaceuracy in the representation of facts. 
^ iii. Magnecrystallic conduction^. 
2836. The beautiful researehes of Plucker in relation to magneoptic phenomena 
cannot have been forgotten, and I hope that my own experiments on magnecrystallic 
results (2454, &c.) are remembered in conjunction with his ; the phenomena described 
by us are, as I believe, due to a common cause, and are the same in kind ; and as far 
as they are presented by pure transparent bodies, are I think brought by Plucker into 
* I must refer here to the important paper by MM. Tyndall and H. Knoblauch on this subject in the 
Philosophical Magazine, 1850, vol. xxxvii. p. 1. M. F. — January 6, 1851. 
