Calamus Aromaticus Pharm. Lond. Acorus, Calamus aromaticus Pharm. Edinb. & C. B. Acorus Calamus Linn. Calamus or sweet-scented flag: a plant with long, narrow, pointed leaves, like those of the narrow iris, of a bright green colour, divided by the longitudinal rib into two unequal portions, one of which is smooth, the other transversely wrinkled. The flowers are imperfect, and stand thick together, forming an elegant spike like the catkin of the hazel, which rises in the bosom of one of the leaves about the middle of its height. The root, which spreads obliquely under the surface of the earth, is long, crooked, full of joints, about an inch thick, somewhat flatted; externally of a greenish. white colour, which changes, in drying, into a brownish yellow; internally white, and of a loose fungous texture. This plant grows plentifully, in rivulets and marshy places, about Norwich and in some other parts of this kingdom, and, as is said, in the canals of Holland: the flowers appear early in the summer, the leaves die in the winter, the roots are perennial. The shops have been usually supplied from the Levant with dried roots, not superiour, and scarcely equal, to those of our own growth.

The roots of calamus have a moderately strong aromatic smell, and a warm, pungent, bitterish taste. Their flavour, when fresh, is unpleasant, approaching in some degree to that of leeks or garlic: by drying, it is greatly improved, but does not become truly grateful. Some report them to be superiour in aromatic flavour to any other vegetables produced in these northern climates; but the specimens I examined fell short, in this respect, of many of our common plants.

Infusions of calamus in water smell strongly of the root, and have a moderately warm and very bitter taste: spirit, applied after water, receives no smell, and scarcely any taste. Tinctures of the root in rectified spirit are warmer and more pungent than the watery infusion, but much less bitter, and of very little smell: water, applied after spirit, gains a considerable bitter-ness, but no smell. It appears, therefore, that water is the most perfect menstruum of the bitter matter, as rectified spirit is of the aromatic, and that the smell of the calamus is covered or suppressed by spirit. The tinctures in both menstrua are of a yellow or brown colour, according as they are less or more saturated.

In distillation with water, there arises a small quantity of essential oil, amounting only to about two ounces from sixty-six pounds of the root (a): both the oil and distilled water have a strong smell, somewhat less grateful than that of the root in substance: the remaining decoction, thus deprived of the aromatic matter, is nau-seously bitter. On distilling the spirituous tincture, the distilled spirit has scarcely any smell or taste of the calamus: the extract, nevertheless, has very little smell, and much less taste than might have been expected in the extract of so warm a root.

Calamus aromaticus was formerly held in considerable esteem as a warm stomachic; and was commonly made an ingredient in bitter tinctures and infusions: among us, it has given place, in this intention, to bitters of a more grateful kind. The root, candied, is said to be used at Constantinople as a preservative against contagion.

(a) Hoffman, Obfervat. physico-chym. lib. i. obs. 1.