We must now pass on to the stones that are employed for handicrafts, and, first of all, whetstones for sharpening iron. Of these stones there are numerous varieties; the Cretan stones having been long held in the highest estimation, and the next best being those of Mount Taygetus, in Laconia; both of which are used as hones, and require oil. Among the water-whetstones, the first rank belonged to those of Naxos, and the second to the stones of Armenia, both of them already[2776] mentioned. The stones of Cilicia are of excellent quality, whether used with oil or with water; those of Arsinöe,[2777] too, are very good, but with water only. Whetstones have been found also in Italy, which with water give a remarkably keen edge; and from the countries beyond the Alps, we have the whetstones known as “passernices.”[2778] To the fourth class belong the hones which give an edge by the agency of human saliva, and are much in use in barbers’ shops. They are worthless, however, for all other purposes, in consequence of their soft and brittle nature: those from the district of Laminium,[2779] in Nearer Spain, are the best of the kind. CHAP. 48.—TOPHUS. Among the multitude of stones which still remain undescribed, there is tophus;[2780] material totally unsuited for building purposes, in consequence of its perishableness. Still, however, there are some localities which have no other, Carthage, in Africa, for example. It is eaten away by the emanations from the sea, crumbled to dust by the wind, and shattered by the pelting of the rain: but human industry has found the means of protecting walls of houses built of it, with a coating of pitch, as a plaster of lime would corrode it. Hence it is, that we have the well-known saying, “that the Carthaginians use pitch[2781] for their houses and lime[2782] for their wines,” this last being the method used by them in the preparation of their must. In the territories of Fidenæ and Alba, in the vicinity of Rome, we find other soft kinds of stone; and, in Umbria and Venetia, there is a stone[2783] which admits of being cut with the teeth of a saw. These stones are easy to be worked, and are capable of supporting a considerable weight, if they are only kept sheltered from the weather. Rain, however, frost, and dew, split them to pieces, nor can they resist the humidity of the sea-air. The stone[2784] of Tibur can stand everything except heat, which makes it crack. CHAP. 49.—THE VARIOUS KINDS OF SILEX.