610

ELEMENTS OF MATERIA MEDICA.

none. Perianth of six pieces or scales, inferior. Stigma sessile. Cap-sule indehiscent. {Hooker.)

Sp. Char. —Ancipitate [two-edged] scape rising much above thespadix. (Hooker.)

Rhizome thick, rather spongy, with many long roots, aromatic, likeevery part of the herbage, but much more powerfully so. Leaves erect,two or three feet high, bright green, near an inch broad. Stalk like theleaves, except being thicker below the spadix, and not quite so tall-Spadix about a foot above the root, a little spreading, two or threeinches long, tapering, covered with a mass of very numerous, thick-set,pale green flowers, which have no scent, except when bruised. A verynarrow wavy membrane may be observed at the base of the spadix, which,perhaps, ought to be taken into the generic character as a spathe {Smith).Perennial; flowers in June.

Hab. —It is a native of this country, growing in watery places aboutthe banks of rivers, and is very plentiful in the rivers of Norfolk , whencethe London market is supplied. It grows also in other countries ofEurope , in Asia , and in the United States .

Description. —The dried underground stem {rhizoma, L.; radix, E-;radix acori veri seu radix calami aromatici , Offic.) occurs in the shops iuflattened pieces four or five inches long, and about as broad as the thumb;jointed, somewhat curved, of a spongy or corky texture internally; of ayellowish brown or fawn colour externally, and buffy, with a slightlyroseate hue, internally. Their fracture is short; their upper surface i smarked transversely with the vestiges of the leaves which were attachedto it; the lower surface has numerous dark points, surrounded by smalllight-coloured elevated circles, from which the roots arise. Their tasteis warm and bitter ; their odour is aromatic. In Germany , the rhizomeis usually peeled before drying it {rhizoma decorticata) ; but the operationis unnecessary and wasteful. In this state the rhizome is greyish whit®and easily pulverizable.

The rhizome should be gathered in spring or late in the autumn, an 1 !dried quickly.

The rhizome of the Yellow Water Iris {Iris Pseud-acorus) is said to b esometimes substituted for that of the true Acorns.

Composition. —The fresh rhizome was analyzed by Troimnsdori(Gmelin, Handb. d. Chem. ii. 1339), w ho obtained the following resultsVolatile oil , O'l; soft resin, 2 3; extractive, with a little chloride °Jpotassium, 3‘3 ; gum, with some phosphate of potash, o'5 ; starchymatter (like inulin), 1'6 ; woody fibre, 21'5 ; and water, 65'7. Meiss» erfound traces of copper in the ashes.

The active constituents are the oil, the resin, and the extractive.

Oil of the common sweet flag (called in the shops oleum calami aromatici) is obtain 6 ^by distilling the fresh rhizome with water. Its odour is similar to, though less ag^fjable than, that of the rhizome. Its colour is yellow. It is imported by the wholes* fdealers in perfumery, and is bought by snuff-makers, so that it is used, I presume, 10scenting snuff.

Chemical Characteristics.— Iodine blackens the rhizome (especia^when it has been boiled), thereby indicating the presence of starch. T 1cold decoction of the rhizome forms, with a solution of iodine, the U"iodide of starch. Acetate and diacetate of lead, and protonitratemercury, cause precipitates with the decoction. These precipi tat