Scented calamus also, which grows in Arabia, is common to both India and Syria, that which grows in the last country being superior to all the rest. At a distance of one hundred and fifty stadia from the Mediterranean, between Mount Libanus and another mountain of no note (and not, as some have supposed, Antilibanus), there is a valley of moderate size, situate in the vicinity of a lake, the marshy swamps of which are dried up every summer. At a distance of thirty stadia from this lake grow the sweet-scented calamus and rush. We shall here make some further mention of this rush as well, although we have set apart another Book for plants of that description, seeing that it is our object here to describe all the different materials used for unguents. These plants differ in appearance in no respect from others of their kind; but the calamus, which has the more agreeable smell of the two, attracts by its odour at a considerable distance, and is softer to the touch than the other. The best is the kind which is not so brittle, but breaks into long flakes, and not short, like a radish. In the hollow stalk there is a substance like a cobweb, which is generally known by the name of the “flower:” those plants which contain the most of it are esteemed the best. The other tests of its goodness are its being of a black colour—those which are white not being esteemed; besides which, to be of the very best quality it should be short, thick, and pliant when broken. The price of the scented calamus is eleven, and of the rush fifteen denarii per pound. It is said that the sweet-scented rush is to be met with also in Campania. CHAP. 49.—HAMMONIACUM. We have now departed from the lands which look towards the ocean to enter upon those which have an aspect towards our seas. (23.) Africa, which lies below Æthiopia, distils a tear-like gum in its sands, called hammoniacum,[576] the name of which has passed to the oracle of Hammon, situate near the tree which produces it. This substance, which is also called metopion,[577] bears a strong resemblance to a resin or a gum. There are two kinds of ammoniacum; that to which the name is given of thrauston, and which bears a resemblance to male frankincense, being the kind that is the most esteemed, and that which is known as phyrama, being of an unctuous and resinous nature. This substance is adulterated by means of sand, which has all the appearance of having adhered to it during its growth: hence it is greatly preferred when the pieces are extremely small, and in the purest state possible. The price of hammoniacum of the best quality is forty asses per pound. CHAP. 50.—SPHAGNOS.