It appears that the new alum was at first distinguished from the ancient vitriol by the denomination of _Rocca_, from which the French have made _alun de roche_, and some of the Germans _rotzalaun_[509]. Respecting the origin of this name very different conjectures have been formed. Some think it is derived from _rocca_, which in the Greek signifies a rock, because this salt is by boiling procured from a stone; and these translate the word _alumen rupeum_, from which the French name is formed[510]. Some are of opinion that alum obtained from alum-stone has been so called to distinguish it from that procured from schists, which is generally mixed with more iron than the former[511]; and others maintain that alum acquired the name of _Rocca_ from the alum-rocks in the neighbourhood of Tolfa[512]. It is to be remarked, on the other hand, that Biringoccio, that expert Italian, confesses he does not know whence the name has arisen[513]. For my part I am inclined to adopt the opinion of Leibnitz, that _alumen roccæ_ was that kind first procured from Rocca in Syria; and that this name was afterwards given to every good species of alum, as we at present call the purest Roman alum[514]. In the fifteenth century there were alum-works in the neighbourhood of Constantinople, from which John di Castro, of whom I shall have occasion to speak hereafter, learned his art. May not these alum-works be those visited by Bellon, and of which he has given an excellent description[515]? He names the place _Cypsella_ or _Chypsilar_, and says that the alum in commerce is called _alumen Lesbium_, or _di Metelin_. The alum procured from Constantinople at present may perhaps be brought from the same spot; but I am not sufficiently acquainted with its situation to determine that point with certainty, for Büsching makes no mention of it. In some maps I find the names _Ypsala_ and _Chipsilar_ on the western side of the river Mariza, Maritz or Maricheh, which was the Hebrus of the ancients; in others stands the name _Scapsiler_ on the west bank of the sea Bouron; and it is not improbable that these may be all derived from the old _Scaptesyle_ or _Scapta Hyla_, where, according to the account of Theophrastus, Pliny and others, there were considerable mines.