Aristotle suggests that perhaps the _Magnet_ is animated. (De Anima.) To comprehend his reasons for maintaining this singular opinion, it would be necessary to understand his theory of motion, as fully exposed in his ‘Auscultationes Naturales.’ Lucretius, with considerable ingenuity, attempts to explain the manner in which the magnet attracts iron. (vi, 1000.) Plato (in Timæo) and Hippocrates (De Sterilibus) also allude to its attractive property. Galen recommends it in dropsies. Dioscorides, Galen, and the other Greek authorities treat of it in a very cursory manner, merely stating of it that it has the same virtues as the hæmatite. The Arabians, more especially Serapion, give a much fuller description of it, which at all events identifies the Magnetis or Heraclean-stone of the ancients with our loadstone, that is to say, the magnetic oxide of iron. It was used by the Arabians as an application to poisoned wounds. See Serapion (De Simpl. 394); Avicenna (ii, 2, 463.) It was used in the practice of medicine from the earliest date. See Hippocrates (De Sterilibus.) Ebn Baithar recommends it in pains of the head and feet, if taken hold of, and in cramps. He copies Aëtius. (ii, 25.) The _Arabian-stone_ is a species of white marble. It is recommended by Dioscorides for hemorrhoids and as a dentifrice. (v, 145.) The _Alabastrites_ is a thick concrete gypsum. See Kidd’s ‘Mineral.’ (i, 63.) Galen says of it, that when burned it is adapted for medicinal use, and that it is sometimes administered in a draught to persons affected with stomach complaints. Dioscorides speaks of its being applied externally in such cases along with wax; calls it discutient, and says it represses the gums. (v, 152.) It would appear that this article is the Lapis eburneus of Rhases, who calls it an astringent and dentifrice. (Cont. l. ult. i, 395.) Geoffroy says that the Smiris is the _Emery_ of the shops. It is held by the mineralogists to be a variety of Corundam. See Cleaveland’s ‘Mineral.’ (278.) A specimen of it, from the Isle of Naxos (which may be supposed a good representation of the ancient Smiris), was found by Tennant to consist principally of alumine, with small proportions of silex and oxide of iron. Dioscorides recommends it in looseness of the gums, and as a dentifrice; he ranks it with septic and caustic substances. (v, 165.) The _Stones in Sponges_ consist principally of the muriate of lime. They were much commended as lithontriptics. See Dioscorides, Pliny, Galen, and Avicenna. The _Ophites_ is a pellucid stone, so called from its serpentine streaks. It was that variety of serpentine called _verde antico_. See Jameson’s ‘Mineralogy.’ According to Dioscorides, it was useful as an amulet in the case of persons stung by snakes, and was also reported to be useful in lethargy and headache. (v, 161.) Galen holds it to be lithontriptic. (De Simpl. viii.) The Arabians copy from Dioscorides and Galen. See Avicenna (ii, 2, 406.)