The writer believes that Tavernier’s snake-stones may all have been tabasheer, or again, while some of them were of this substance, others may have been artificially compounded by the authorized dealers of the Brahmin caste. The instance he gives of the successful use of such a stone is not altogether incredible, as, should one of the less active poisons be sucked out of a wound shortly after this were inflicted, a cure might well be effected. In view of the great difference in the virulence of poisons and the varying degrees of the sensibility to toxic effects, it is not strange that the snake-stones should sometimes seem to give good results. Tavernier states that these stones were brought to India by Portuguese soldiers returning from service in Mozambique.[472] For successful use a pair of them were needed, so that, when applied to a snake-bite, as soon as one became saturated with the venom the other could be immediately substituted. To have them always at hand, those natives fortunate enough to own a pair of _pedras de cobra_ carried them about in a little bag.[473] A curious traditional belief is current in some parts of India, notably in Ceylon, to the effect that the male cobra, during the night, uses a certain luminous stone to lure its prey and to attract the female. This is probably the chlorophane, a variety of fluorite, a substance which shines with a phosphorescent light in the darkness, and this quality, quite mysterious in the eyes of the natives, may have induced them to associate the stone with the snake, the epitome of all subtlety and cunning. Serpent-stones were supposed to exist in both ancient and medieval times, and the belief in their existence is widespread among many races of mankind. A chlorophane is also found in the microlite localities of Amelia Court House, Virginia. The writer made a series of experiments and noted that some of these specimens emit a phosphorescent light at a low temperature. The material occurs in Siberia, and Pallas describes a specimen from this locality. When subjected to the heat of the hand, it gave out a white light, in boiling water a green light, and when placed on a burning coal a brilliant emerald-green light, visible at a considerable distance. Similar phenomena have been observed by the writer, who has found that very slight attrition, even the rubbing of one specimen against another in the dark, will produce phosphorescence.[474]