The alchemists were familiar with alum and knew it to be a combination of sulphuric acid with an unknown earth. Van Helmont was the first to employ alum as a styptic in uterine hæmorrhage, and Helvetius made a great reputation for a styptic he recommended for similar cases. His pills were composed of alum 10 parts, dragon’s blood 3 parts, honey of roses q.s., made into 4 grain pills, of which six were to be taken daily. Alum and nutmeg equal parts were given in agues. Paris says the addition of nutmeg to alum corrects its tendency to disturb the bowels. It has also been advocated in cancer and typhoid, but these internal uses have been generally abandoned. Spirit of Alum is occasionally met with in alchemical writings. It was water charged with sulphuric acid obtained by the distillation of alum over a naked fire. Until the fifteenth century the only alum factories from which Europe was supplied were at Constantinople, Smyrna, and Trebizonde. Beckman relates that an alum factory was founded in the Isle of Ischia, on the coast of Tuscany, by a Genoese merchant named Bartholomew Perdix, who had learnt the art at Rocca. Very soon afterwards John de Castro, a Paduan who had been engaged in cloth dyeing at Constantinople but had lost all his property when that city was captured by Mahomet II in 1453, was appointed to an office in the Treasury of the Apostolic Chamber, and in the course of his duties found what he believed to be an aluminous rock at Tolfa, near Civita Vecchia. He asked the Pope, Pius II, to allow him to experiment, but it was some years before the necessary permission was granted. When at last the truth of Castro’s surmise was established the Pope was greatly interested. He looked upon the discovery as a great Christian victory over the Turks, and handsomely rewarded de Castro, to whom, besides, a monument was erected in Padua inscribed “Joanni de Castro, Aluminis inventor.” The factory brought in a splendid revenue to the Apostolic exchequer, and the Pope did his utmost to retain the monopoly, for when in consequence of the extravagant prices to which the Tolfa alum was raised merchants began again to buy the Eastern product his Holiness issued a decree prohibiting Christians from purchasing from the infidels under pain of excommunication. Later, when, in Charles I’s reign, Sir Thomas Challoner discovered an aluminous deposit near his home at Guisborough in Yorkshire, and persuaded some of the Pope’s workmen to come there to work the schist, he and those whom he had tempted away were solemnly and most vigorously “cursed.”