You will remember my saying, no doubt, that there are numerous instances of the prettiest of girls avoiding the presence of mirrors?  You will have gathered the explanation of this singular phenomenon from the contents of my last letter. Quicksilver is one of the metals that have the most nauseating reaction on sensitive human beings. When one of the latter goes near a large-surfaced mirror, he feels the unpleasant effect of the quicksilver diffused over his entire body; it seems to him as though a lukewarm sickly breath came upon him; he feels himself pushed and driven off and, if he chooses to resist, he is attacked by stomach-ache, a feeling of indisposition, headache, and even vomiting; he has to give way. This attains to such a pitch with increasing experience that, in the case of high-sensitives, it leads to shuddering in the presence of a mirror, so that they cover it up when they cannot put it out of the way.

Let us now, please, glance back at the subject of disgust as caused by tablespoons of German silver, argentan, new silver, and Chinese silver. Copper, which forms the foundation in all these compositions, is about as strongly odic a body as you can get for a very nauseating and disgusting reaction. Electroplate it as you will, it is all in vain; the copper exercises its odic effect from beneath the plating, becomes unbearable even to medium-sensitives, and as to high-sensitives, it not unfrequently causes them stomach-ache, and even cramp of the tongue and lockjaw. I have often enough heard lady sensitives say that they can wear no metal ornaments, because they do not feel comfortable with them; that they cannot bear working with a metal thimble, and must have an ivory one; that they cannot fix a steel busk to their corsets; nay, that they cannot even endure hairpins in their hair—and all simply on account of the disagreeably tepid odic reaction of the metal.

To sensitive girls engaged in domestic service brass pestles and mortars, copper cooking utensils, and particularly flat-irons made of metal, are an abomination. Our respected mill-owner of Azgersdorf (near Vienna), Mr. J. Fichtner, a good medium-sensitive, has had all brass utensils removed from his kitchen, as he cannot bear partaking of food or drink that has been prepared in brass.

Though metals be covered over with paper, linen, or other light substances, high-sensitives are always able to detect where the pieces of metal lie hidden, merely by the sense of feeling in the palm of their left hand which they hold above. In this connection can you fail to remember the ninth letter of this series, in which I spoke of friction by water and Monsieur Sourcier?  Given the presence of metals, say a sum of money in coinage to a fair amount buried underground, but not too deep beneath the surface, there can be no doubt that a high-sensitive would discover such objects by his sense of feeling, more easily and quickly than the sensitives of medium powers found out the water-conduit in my grounds.

Now take the case of a vein of lead-glance, copper pyrites, red silver ore, and the like, cropping up not too far beneath the surface—as they are so often found to lie hidden a few feet only beneath the vegetable soil—and of a high-sensitive directing his steps above them with some degree of attention; can you doubt even for a moment, after what you now know, that he would become aware of them through his sensations, and would be able to point out the exact spot where they are located?

And other things too, such as the outcrops of coal-beds, are sure to have a quite different effect on a man highly sensitive to odic excitation, than the sandstone and shale in which they lie. When such a man has previously observed the odic sensations produced upon him by masses of coal, and recorded them in his memory, he will at once be able to tell when he is walking over a coal-bed. No other man will be able to perceive anything of the matter, but a high-sensitive will tell you straight off with perfect assurance: there, or there beyond, this mineral or that lies underground; and excavation will justify the apparent miracle; which up to the present has seemed all the more astonishing from the fact that the finder has been unable to account to himself satisfactorily for the matter, and much less to anyone else.

The miracle is now made plain; it is nothing else than a purely physical influence of the odic dynamid on the human nervous system; it takes effect like an occult sense, about which no one is in a position to draw any conclusion; and a large number of the incidents ascribable to instinct in animals will find their explanation on the same lines as those I have just given for the metal- and ore-finder.

And now, my friend, there you have in their completeness the final secrets of the divining-rod, not, it is true, of the rod as such in its literal sense, with its alleged dipping and twisting and thrashing out—I take all that to have been nothing more than the hocus-pocus of the art, contrived for the curious multitude, to whom those pestered by their enquiries had to give some tangible reply—but of the hitherto deep-hid, substantial kernel of the matter.

The perception of the sensitive can be uncommonly developed by practice. When I get new people to deal with, their indications are sometimes strikingly subject to fluctuation, and it is only after two or three sittings that everything begins to clear up and become definite. But a prolonged period of practice in these perceptions brings decision and readiness, and I have medium-sensitives who, in virtue of a six and seven years' familiarity, have attained to an acuteness of discrimination that more often than not makes them superior to nigh-sensitives who are novices.

Such men will in future be of great utility in relation to the counterfeiting of goods. Anyone who is a good sensitive is fairly sure to possess the faculty of distinguishing genuine gold and silver from the plating on copper. But this faculty can be extended by practice for all sorts of mixtures, so much so that the stock in a druggist's shop, for instance, could be judged in the matter of its retention or loss of efficient principles. Indeed, I shall perhaps show you later on what astonishing diagnoses of sick patients can be obtained from the mere sense of feeling exerted by sensitives in good health.