Petroleum has been called by many other names. Oil of Peter or Petre was a common one, meaning, like petroleum, simply rock oil. Myrepsus, in the thirteenth century, refers to it as Allicola. The monks called it sometimes oil of St. Barbarus, and oil of St. Catherine. Dioscorides said naphtha was useful as an application in dimness of sight. Two centuries ago it was occasionally given in doses of a few drops for worms, and was frequently applied in toothache. Petroleum Barbadense, Barbadoes tar, had some reputation in pectoral complaints in the seventeenth and eighteenth centuries, and was admitted into the P.L. as the menstruum for sulphur in the balsamum sulphuris Barbadense. PHOSPHORUS. Phosphorus, or its Latin equivalent, Lucifer, was the name given by the ancient astronomers to the planet Venus when it appeared as a morning star. When it shone as an evening star they called it Hesperus. Do we invent such seductive names now, or do they only seem attractive to us because they are ancient or foreign? The phosphorescent properties of certain earths had been occasionally noticed by naturalists, but no observation of the kind has been traced in ancient writings. The earliest allusion to a “fire-stone” known occurs in the work of a gossipy French historian named De Thou. In a history of his own times this writer relates that in 1550, when Henri II made his state entry into Boulogne on the occasion of its restoration to France by the English, a stranger in foreign costume presented the king with a fire-stone which, he said, had been brought from India. De Thou narrates that this wonderful stone glowed with inconceivable splendour, was so hot that it could not be touched without danger, and that if confined in a close space it would spring with force into the air. Sometime early in the seventeenth century, a shoemaker of Bologna, one Vincent Cascariolo, who, in addition to his ordinary business dabbled in alchemy, discovered a stone in the neighbourhood of his city which was luminous in the dark. The stone, which is now known to have been a sulphate of barium, and which the shoemaker calcined, ground, and formed into little round discs about the size of a shilling, and sold for a fancy price, was called the sun-stone. The discs, exposed to a strong light for a few minutes and then withdrawn into a dark room, gave out the incandescent light which we know so well. The discovery excited keen interest among scientific men all over Europe. [Illustration: JOHANN KUNCKEL. (From the Collection of Etchings in the Royal Gallery at Berlin.) ]