12. Heliotropium[359] ... receives the sun-light after the manner of a looking-glass, and reveals the eclipses of the sun, showing the moon passing under. In the case of this gem there is also a most manifest proof of the shamelessness of the magi, because they say its wearer is not visible if he takes an infusion of the plant heliotrope and in addition utters certain charms. [359] Striped jasper. Chapter 8. On red gems. 1. ... The magi assert that [coral] resists thunder-bolts,—if it is to be believed. Chapter 10. On white gems. 4. _Galactites_ (milk-stone) is milk-white, and being rubbed it gives a white fluid that tastes like milk, and being tied on nursing mothers it increases the flow of milk. If it is hung on the necks of children it is said to create saliva, and it is said to melt in the mouth and take away the memory. Chapter 13. On crystals. 1. It is said that crystal glitters and is of a watery color because it is snow that has hardened into ice in the course of the years.... It is produced in Asia and Cyprus, and especially in the Alps of the north, where there is no hot sun even in summer. Therefore the ice itself is bared, and hardening through the years gives this appearance which is called crystal. This, being set opposite to the rays of the sun, so seizes upon its flame that it sets fire to dry fungi or leaves. Its use is to make cups, but it can endure nothing but what is cold. 2. _Adamas_ ... Though this is an unconquerable despiser of the steel and of fire, yet it is softened by the fresh, warm blood of stags, and then is shattered by many blows of an iron instrument. 3. It is said to reveal poisons as does amber (_electron_), to drive away useless fears, to resist evil arts. Chapter 14. On glowing gems. 7. _Dracontites_ is forcibly taken from the brain of a dragon, and unless it is torn from the living creature it has not the quality of a gem; whence magi cut it out of dragons while they are sleeping. For bold men explore the cave of the dragons, and scatter there medicated grains to hasten their sleep, and thus cut off their heads while they are sunk in sleep, and take out the gems. Chapter 15. On yellow gems. 17. _Glossoptera_ is like the human tongue whence it took its name. It is said to fall from heaven when the moon is in eclipse, and the magi attribute great power to it, for they think that to it the motions of the moon are due. 21. There are also certain gems which the heathen use in certain superstitions. 22. By the fragrance of the _liparia_,[360] they relate that all wild beasts are summoned. By the _ananchitis_[360] in divination by water they say the likenesses of demons are summoned. By the _synochitis_[360] they assert that the shades of those below that have been summoned forth, are held. [360] Unknown. 23. _Chenelites_ is the eye of the Indian tortoise, of a varied purple. By means of this magi pretend that the future is foretold, if it is put on the tongue.