part ii. Materia Medica. — Linum usitatissimnm. 367

lour, which, however, is very evanescent: all acids and salts,with an excess of acid, change it to red, which is again de-stroyed, and the blue restored by the addition of alkalies; andeven exposure to the air of a room, in which many people areassembled, reddens the watery infusion. The tincture is leastliable to change when kept, if it be reddened by an acid, andkept in close vessels.

Use. — This species of lichen is said to have been " admi-nistered medicinally, with an intention of allaying the tickling-attendant on phthisis, and in hysterical coughs 1 ;" but we mustsuppose the recent lichen is meant, or before it has undergoneany preparation as a colouring matter. We know of no othernse of the prepared lichen than as a dye stuff, or a chemicaltest of the presence of acids ,• and it is certainly the most deli-cate.

LINUM. 2 Spec. Plant. Willd. i. 1533.CI. 5. Ord. 5. Pentandria Pentagynia. Nat. ord. Gruinales, Linn.

Caryophylleas, Juss.G. 590. Calyx five-leaved. Petals five. Capsule five-valved, ten-

ceWed. Seed solitary.

* With alternate leaves.

Species 1. L. usitatissimnm. Common Flax. Med. Bot. Id edit.* 566. t. 202. Smith Flora Brit. 342. Curtis Lond.fasc. 5. t. 22.

* * With opposite leaves.

Species 26. L. catharticum. Purging Flax. Smith Flora Brit. 344.Eng. Bot. 382.

1. Linum usitatissimum.Officinal. Lini usitatissimi semina, Lond. Edin. Linum ;semina, Dub. Linseed, and Linseed oil.

Syn. Grains de Lin (F.), Leinsaamen; Flachsaamen [G. ), Semi di Lino (/.),Laxor (£.), Busrue {Arab.), Tisi (H.), Atasci (&».)•

The common flax is an annual plant, flowering in July. Itis supposed to have been originally brought from those parts ofEgypt which are annually inundated by the rising of the Nile;but it is now found growing wild in this country, and is cul-tivated in most parts of Europe. The root is simple andfibrous. The stem is erect, round, smooth, slender, and leafy ;branched, with a panicle at the summit, and rising about twofeet in height. The leaves are small, lanceolate, entire, ob-scurely three-nerved, smooth, sessile, standing nearly upright,and alternate on both the stem and branches. The flowersare petiolate; the calyx persistent, composed of five sharp-pointed, keeled, tvi-ncrved, ovate leaflets; and the corolla con-sists of five notched, oblong, sky-blue, streaked petals, whichspread into funnel-formed blossoms. The filaments are white,dilated, and slightly united at the base; the germen is ovate,and crowned with five blue, thread-like, spreading, reflected

Translation of the Dublin I'harmacop. p, 165.

tuyov Dioscoridjs.