The ancients procured their alum from various parts of the world. Herodotus mentions Egyptian alum; for he tells us that when the people of Delphos, after losing their temple by a fire, were collecting a contribution in order to rebuild it, Amasis king of Egypt sent them a thousand talents of alum[494]. In Pliny’s time the Egyptian alum was accounted the best. It is well known that real alum is reckoned among the exports of Egypt at present, but I am acquainted with no author who mentions the place where it is found or made, or who has described the method of preparing it. The island of Melos, now called Milo, was particularly celebrated on account of its alum, as we learn from Diodorus Siculus, Celsus, Pliny and others, though none was to be found there in the time of Diodorus[495]. This native vitriol has been observed in the grottos of that island by several modern travellers, especially Tournefort[496], who very properly considers it as the real alum of the ancients. The islands of Lipara and Strongyle, or, as they are called at present, Lipari and Stromboli, contained so great a quantity of this substance, that the duty on it brought a considerable revenue to the Romans[497]. At one period, Lipari carried on an exclusive trade in alum, and raised the price of it at pleasure; but in that island at present there are neither vitriol nor alum-works. Sardinia, Macedonia, and Spain, where alum was found formerly, still produce a salt known under that name[498]. When our alum became known, it was considered as a species of the ancient; and as it was purer, and more proper to be used on most occasions, the name of alum[499] was soon appropriated to it alone. The kinds of alum however known to the ancients, which were green vitriol, maintained a preference in medicine and for dyeing black; and on this account, these impure substances have been still retained in druggists’ shops under the name of _misy_, _sory_, &c. But a method was at length found out of procuring thence crystallized martial salts (salts of iron), which obtained the new name of _vitriol_. This appellation had its rise first in the eleventh or twelfth century; at least I know no writer older than Albertus Magnus by whom it is mentioned or used. Agricola conjectures that it was occasioned by the likeness which the crystals of vitriol had to glass. This is also the opinion of Vossius[500]; and it is very singular that Pliny says nearly the same thing; for he observes, speaking of blue vitriol, the only kind then known, that one might almost take it for glass[501].