The fumes of jet are mentioned as a remedy for the pest in one of the earliest Greek medical treatises, written by Nicander, who flourished in the second century B.C. He declares that the most virulent pestilence could be driven away if the bedrooms were fumigated with the smoke of the slow-burning jet.[292] The plague was called the black plague and naturally the aid of a black substance was sought to cure it. For Pliny, jet was endowed with many medicinal virtues. Its fumes were a cure for hysteria and were said to reveal the presence of a latent tendency to epilepsy; connected with this in some way was the curious belief, repeated by later authors with certain variations, that these fumes could also be used as a test of virginity. When powdered and mixed with wine, jet relieved the pains of those suffering from toothache, and if the powder were combined with wax, a salve was produced that gave very beneficial results in cases of scrofula.[293] Even as a toilet preparation jet was recommended for use, and a most excellent dentifrice is said to have been made from it. In this connection jet was credited with tonic as well as cleansing properties, as is shown by the words of Bartholomæus Anglicus, who declares that this material was especially beneficial for “feeble teeth and waggyng,” since it strengthened them and made them firm.[294] The delusions and hallucinations of melancholic subjects were believed to be put to flight by the power of jet, either in its solid form or when reduced to a solution. The fact that this material was often used for the beads of rosaries was thought to have some connection with its supposed virtues, since the bad dreams or dreadful hallucinations sometimes accompanying melancholia were designated as “demons,” and thus the prayers counted off on jet beads might be supposed to have the greater power to banish the devil and his black angels. The old writer who cites these particulars about jet, adds that there was to be found in the river Nile a black stone the size of a bean, at sight of which dogs would stop barking, and which also drove away evil spirits. Here we have another among many instances of the curious blending of the doctrines of sympathy and antipathy, the black stone repelling the imps of darkness and nullifying the spells of the Black Art.[295] Lapis Armenus The _lapis Armenus_ was well known to the Arabs under the name _hajer Armeny_, and their medical writers describe it quite accurately and distinguish it from the somewhat similar lapis lazuli, with which it was often confused in ancient times. Ibn Beithar states that if properly prepared it would not provoke nausea, as was otherwise the case. It was said to cause a very abundant evacuation of bile and must have been regarded as an efficient remedy for the bilious disorders so general in warm climates.[296]