I have headed these letters of mine Odic-Magnetic Letters, "But why magnetic? What has magnetism got to do with them?" you ask. My answer must almost be, "Little or nothing at all." But it has pleased the world to call a number of the phenomena which come in here magnetic, and I have to accommodate myself to the nomenclature demanded by the fashion of the day. The occasion for my doing so lies in the circumstance that magnetism has for its collaterals certain odic forces, just as sunlight and moonlight have a retinue of them, just as they proceed from the poles of a crystal, and just as they flow from numerous sources that have nothing even remotely in common with magnetism as we have so far understood it. Let us take a glance at the mutual relations of magnetism and od.
Lay a good rod-magnet transversely across the comer-of a table, so that both ends project, as you did with the large crystal. Get the table into such a position that the rod will be left lying along the meridian, like the needle of a compass, with the northward pole to the north and the southward pole to the south. Now bring in a sensitive, and get him to gradually approach first one pole, then the other, to a distance of four or five inches, with the palm of his left hand. By this proceeding you will get the same declarations from him that he made in the case of the crystals, namely, that one of the poles, in this case the one turned towards the north, sends a cool breath of air to his hand, and that the other turned towards the south gives out a lukewarm, mawkish breath.
Again, you can set a glass of water at each pole of the magnet, and after six or eight minutes get the sensitive to taste them. He will pronounce the glass it the pole turned to the north fresh and cool, and I hat at the pole turned towards the south lukewarm and disgusting; and, if you wish to challenge our chemists again, they will get angry and, to free themselves from their embarrassment, will bluntly contest the observation made, though it be as clear as day, and tell you that it is not the fact. It is for you to smile at the simplicity evinced now and again ex cathedra—as if a truth of nature could be turned into an untruth by unsupported contradiction. In spite of themselves these gentlemen will have to think out some better answer before long.
You will naturally assume that the conjectures which took me into the dark with the crystals must have risen up to my mind for the case of magnets as well. I made my first experiment of this sort with Miss Mary Nowotny in Vienna during April 1844, and repeated it with other sensitives in the dark chamber a hundred times after. It was with satisfaction and delight that I ascertained my conjectures to have been justified, for she straightway stated that at both ends of the magnet-rod a flame was burning, luminous and fiery, smoking and sending out sparks, at the end to the north blue, at the end to the south yellow-red. But make the easy experiment yourself, and then vary it. Set the rod-magnet up on end, with its southward pole uppermost, and you will be told that the luminous body increases, mounting almost to the roof of the chamber if the magnet is strong enough. Indeed it will go so far as to produce an illuminated spot of a somewhat rounded shape on the ceiling itself, one, two or as many as three feet in diameter, and so bright that, if the sensitive is sufficiently responsive to excitation, he will be able to describe the decoration he sees there.
But I warn you not to omit any of the precautionary measures I have prescribed as to absolute darkness and preparation of the eyesight in darkness for hours at a time. If you omit one, your assistant in the experiment will see nothing; you are labouring in vain; and the exactness of my statements is exposed to undeserved suspicion.
A more beautiful appearance still will be presented by the luminous phenomenon, if a horseshoe magnet be used, set vertically with both poles upwards. I have in my possession a nine-layered horseshoe magnet with a lifting power of 100 lbs.; from each pole of this instrument all sensitives see a body of fine light—that is, two lights, one beside the other— streaming out; they do not attract, do not counteract, do not influence each other as the magnetic forces of the two poles do, but quietly stream up on high, one beside the other; they swarm with innumerable little points of white light, and together form a column of light the size of a man's body, which everyone who saw it described as strikingly beautiful. It goes up vertically to the ceiling and there forms an illuminated round superficies of almost two yards diameter. If the spectacle is kept in view for a good time, the whole roof of the chamber becomes gradually visible.
If a magnet such as described stand upon a table, the naming emanation lights up the surface of the latter and any ornaments set upon it for ells around. If a hand be interposed, a shadow is visibly thrown.
If any flat object, such as a bracket, a pane of glass, or a sheet of metal, is held horizontally in the flame-like phenomenon, the latter takes a bend round it and streams away from it underneath, just as the flame of any other fire acts when a pan or saucepan is brought into it. If you blow or breathe on it, it flickers just like the flame of a candle would do. If a draught is set up, or if one carries the magnet about, the flame goes on one side in the direction taken by the current of air, like the flame of a torch in motion. If a burning-glass be put to it, it admits of its light being gathered and condensed at the focus. The phenomenon is consequently quite a material one, and has many qualities in common with ordinary flame.
When two magnet-flames of the kind are brought together, so as to cross each other's path, they do not disturb each other by attractions or repulsions, but interpenetrate and keep without hindrance on their course. When one is stronger than the other, endowed apparently with a stronger power of projection, it penetrates the weaker, so that the latter is cloven and courses around it on both sides. The same takes place when a rod is held in it; the rod splits the flame in two, and the flame reunites behind the rod. And just as the sensitives saw the crystals in a subtle body of light which penetrated their entire substance, so they now see the steel of the magnet fused through and through with a kind of whitish glow. Electro-magnets behave in just the same way.1
These qualities possess, as you will easily perceive, no parallelism with those of magnetism; they are characteristically odic. If you compare a crystal of gypsum spar with a rod-magnet, both' as near as maybe of the same weight, you find no material difference between the odic emanations from the like poles, either in the effect upon the sensorium or in the matter of luminosity. In fact the crystal is even superior to the magnet in odic power; its cool and warmth is more distinct, and its strength of light greater. But a crystal has no magnetism. Here, then, you have a case of od associated with magnetism, and a case of od without magnetism, and in both cases you have od of like strength. It cannot consequently be in any way asserted that od is a connecting link with magnetism, or that it is only one cf the qualities of magnetism, or that it is magnetism itself. Od is found in the crystal quite apart from magnetism, and I shall quote you quite a number of just as striking examples in which od presents itself in the highest degree of force, while any magnetism (in the ordinary sense) is far from being present.
Od must therefore be regarded as a force in itself, which shows itself in the train of magnetism, as it enters into the train of crystals, sunbeams, and many other natural phenomena which we shall touch upon. We know the great resemblance that exists between magnetism and electricity; we know that one appears so often as a sequel to the other, and vice versa, that we come near taking them to be identical. Light and heat are on the same footing; one calls the ether forth, and every moment each is being transformed into the other; and, in spite of all that, we are unable to lay our finger anywhere on the common point of departure from which they both have their origin. So it is with od. We suspect, I grant you, that these dynamic phenomena emerge in the last instance from a common source; but so long as we are not in a position to identify the unit which gives them their origin, so long nothing remains for us to do but to treat of electricity, magnetism, light, heat, and so on, as constituting, each one of them, a separate group of phenomena in itself.
In consequence of the fact that we find ourselves unable to list the numerous odic phenomena under any of the known natural forces, nothing remains for us but to bring them together and treat thorn as a special group. That they yield in no respect, either in range or importance, to those already enjoying civic rights in our schools of physics, my following letters will give you good reason to be convinced.
1 For detailed treatment of these light-phenomena of magnets, with necessary proofs, see the treatise, Researches in the Forces of Magnetism, Electricity, Heat, light, etc., in their relations to Vital Force (Uniersuchungen uber die Dynamide des Magntttsmus, dev Eltktricitit, der Wdrme, des l.ichts, etc., in ihren Beitehungen sur Lebenskraft), by Baron von Reichenbach. Vieweg 1850; Brunswick.