Faraday to William Whewell   8 December 1845

Royal Institution | 8 Decr. 1845

My dear Sir

Think, first of all, of two small bars about 2 inches long & 1/4 or 1/2 an inch in width; and imagine them freely suspended in a horizontal position so that they can revolve on a vertical axis. Let these bars be Iron and heavy Glass; or, as a better known thing Phosphorous. Place these bars in succession between two powerful magnetic poles N & S. The iron bar, as all know, will point axially or from pole to pole, & if nearer one pole than the other, or near a single pole will be attracted bodily. - Place the bar of Phosphorous in the same position & it will point equatorially or across the magnetic axis & if nearer one pole than the other, or near a single pole will be bodily repelled. With the iron ranks Nickel, Cobalt, Titanium, Manganese, Cerium, (and perhaps another metal Chromium) and all their compounds, salts & solutions even, (except perhaps those in which the compound acts the part of an acid): - with the phosphorous ranks all other bodies when in the solid or liquid state[.]

This is my present discovery which I hinted before to you¹ - and I have not time to go further into it for I am very hard at work.

But:- we have used the word Magnetic to indicate an action after the manner of iron[.] Now here is another action which is to that, as Pos is to Neg Electricity, or as any other relation, dual in its character. I have, before the discovery of this power, been in the habit of calling iron &c Magnetics, & the other bodies as water earth &c dimagnetics but now what I am to call this new mode of action? what terms am I to use which shall express for magnetism the two states on the opposite sides of the normal or neutral point? We have the Normal condition perfect in Air & all gaseous bodies & I believe I have found one solid substance very near to it[.]

In Haste | Most Truly Yours | M. Faraday

Rev. Dr. Whewell | &c &c &c