The most powerful action was that exerted by hematite, the oxide of iron in this substance inducing a kind of paralysis, with a sensation of inner chill; this condition could only be relieved by the application of a piece of witherite. Octahedrons of magnetite (loadstone) caused a sensation of heaviness and convulsive movements of the limbs, even when the material, wrapped up in paper, was brought near the subject. Spinel, in whose composition oxide of chromium enters, caused the same symptoms as loadstone, except that in this case the force seemed to exert itself from the hand upward along the arm, while with the loadstone the action was downward along the arm to the hand, owing to the attractive quality of this magnetic iron. Ruby called forth a sensation of coldness in the tongue, and rendered this member so heavy that only incoherent sounds could be emitted; the fingers and toes also became cold, and the body was agitated by a violent shivering; but to all these bad symptoms succeeded a sense of elasticity and well-being, not, however, without a vague fear that the stone might cause a renewal of the physical depression. When chrysoprase was used, chills and shivering resulted, beginning at the breast and spreading thence over the whole body. [Illustration: ROCK-CRYSTAL AMULET SET IN SILVER. Bohemian, tenth century. Field Museum of Natural History.] [Illustration: ROCK-CRYSTAL PLACQUE, ANCIENT MEXICAN. Field Museum Collection, Chicago.] We have touched upon the hypnotic influence exercised by gems, but there can be no doubt that the subject has not been as carefully studied as it deserves to be. That the hypnotic state can be induced by gazing fixedly upon a bright object held just above the eyes is a well-known fact, but quite probably a similar though not so pronounced effect results from gazing on a bright object just before the gazer’s eyes. In the case of colored precious stones, the effects of the various color-rays combine with the light effects and strengthen the impression upon the optic nerve. All this, however, concerns only the purely physical impression, but we know that very often the hypnotic state is produced by a mental impression, by the belief, or the fear, that the state will supervene. With precious stones as hypnotizing agents, the mental impression is widely different, for here the physical impression is heightened by the consciousness of the value and rarity of the material. The fascination that a fine set of jewels, with all their sparkle and color, exercises upon the mind of a woman who sees them in their glorious radiance on the neck, the arms, and the head of another woman, is not only due to the beauty of the spectacle, but is largely owing to the consciousness that they are rare and valuable objects and are perhaps eloquent witnesses of the power of love. A dash of envy sometimes serves to render the emotion more complex.