26 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXV.) 
still greater to those, if there be any, who, assuming that magnetic and diamagnetic 
bodies are alike in nature, must assume that there are like currents in both ; for it 
does not seem possible to add (for instance) phosphorus having such a magnetic 
constitution to space, supposed to be of a similar constitution, and yet to have as a 
result a diminution of the magnetic powers of the space. 
2789. As space therefore comports itself independently of matter, and after another 
manner, the different varieties of matter must, in relation to their respective qualities, 
be considered amongst themselves. Those which produce no effect wdien added to 
space, appear to me to be neutral or to stand at zero. Those which bring with them 
an effect of one kind will be on the one side of zero, and those which produce an 
effect of the contrary kind will be on the other side of zero ; by this division they con- 
stitute the two subdivisions of magnetic and diamagnetic bodies. The law which I 
formerly ventured to give (2267. 2418.), still expresses accurately their relations; for 
in an absolute vacuum or free space, a magnetic body tends from weaker to stronger 
places of magnetic action, and a diamagnetic body under similar conditions from 
stronger to weaker places of action. 
2790 . Now that the true zero is obtained, and the great variety of material sub- 
stances satisfactorily divided into two general classes, it appears to me that we want 
another name for the magnetic class, that we may avoid confusion. The word mag- 
netic ought to be general, and include all the phenomena and effects produced by the 
power. But then a word for the subdivision, opposed to the diamagnetic class, is 
necessary. As the language of this branch of science may soon require general and 
careful changes, I, assisted by a kind friend, have thought that a word not selected 
with particular care might be provisionally useful ; and as the magnetism of iron, 
nickel and cobalt, when in the magnetic field, is like that of the earth as a whole, so 
that when rendered active they place themselves parallel to its axis or lines of mag- 
netic force, I have supposed that they and their similars (including oxygen now) 
might be called paramagnetic bodies, giving the following division : — 
If the attempt to facilitate expression be not accepted, I hope it will be excused. 
2791 . From the presence of oxygen in the air, the latter is, as a whole, a magnetic 
medium of no small power. Hence all the comparative experiments on the diamag- 
netic condition of other gases, made by passing streams of them through it and 
through each other*, require a correction, which occasionally may place some of 
these bodies on the paramagnetic side of zero. Even solid and fluid substances may 
be thus affected ; and the preliminary list, which I formerly gave (2424.), will need 
alteration in this respect. J hope soon however to have the means of ascertaining, 
* Philosophical Magazine, 1847, vol. xxxi. pp. 407, 420, &c. &c. 
