2 Spec. Plant. Willd. ii. 772. Cl. 10. Ord. 5. Decandria Pentagynia. Nat. ord. Oxalideae. G. 918. Calyx five-leaved. Petals connected by claws. Stamens unequal, the five shorter exterior ones connected at the base Capsules opening at the corners, five-cornered. *** Leaves ternate, scape one-flowered. Species 25. O. Acetosella. Wood-sorrel. Med. Pot. 2d edit. 563.

t. 201. Smith, Flor. Brit. 491. Jacquin's Oxalis, 114. t. 80. f. 1. Lindleys Synopsis, 59. Officinal. Acetosella, Lond. Wood-sorrel.

Syn. Oseilledes Bucherons (F.), Sauerklee (G.), Zuurklaver (Dutch), Skovsyne (Dan.), Harsyra (Swed.), Szezawik (Polish), Luggiola Acetosa salvatica (I), Oxalide acederilla (S.), Trevo azedo (Portug.).

This is an indigenous perennial plant, found in woods, under hedges, and other shaded places, and flowering in April and May; the root is horizontal, toothed, fleshy, and of a reddish colour. The leaves are all radical, ternate like the trefoil, and petiolate; with the leaflets obcordate, very entire, hairy, of a yellowish green colour, and purplish underneath. The scape or flower-stalk is furnished with two scaly bractes, placed about an inch and a half beneath the flower, which is subnutant, delicate, and of a flesh-colour streaked with red. The calycine leaflets are oblong, oval, acute, ciliated, and purple at the tip. The corolla is bell-shaped; with the claws of the petals upright, and the borders obovate, rounded, and spreading: the filaments are somewhat connate at the base, and furnished with oblong, incumbent anthers; and the styles smooth, rising from an ovate germen. The capsule is membranous, and contains two seeds in every cell. Each seed is invested with a fleshy white tegument, resembling an aril, which is, at first, smooth and closed on every side, but at length, opening at the apex elastically, it rolls back and throws off the seed with considerable force.1

1 The milk of the ewe is seldom used either as aliment or medicine. It contains more cream and less whey than cow's milk, but the butter yielded by it never' acquires a proper consistence. It is made into cheese in Scotland, which is bitterish; and, when old, warm, biting, and resembling Parmesan cheese in flavour.

Dioscoridis.

Qualities.-This plant is inodorous, and has a pleasant acidulous taste. The expressed juice reddens vegetable blues, coagulates milk, and instantly precipitates lime from its solutions. Its active principle is binoxalate of potassa, which is obtained crystallized from the expressed juice, and sold in the shops under the name of Essential salt of lemons.2 The same salt may be formed by cautiously dropping a solution of potassa into a saturated solution of the oxalic acid, obtained from sugar by the action of the nitric acid; the binoxalate precipitates as soon as the proper quantity of alkali is added.3 It consists of two equivalents of oxalic acid = 72.48 +1 of potassa=47.15 + 7 of water = 63 =192.63. It crystallizes in small rhomboids.

Medical properties and uses.-Wood-sorrel is refrigerant and antiseptic. Boiled in milk it forms a pleasant whey, which may prove a useful refrigerant in fevers, as may also the expressed juice, or the superoxalate obtained from it diluted with water : but although they are much extolled in inflammatory, bilious, and putrid cases, by the Continental physicians, yet their place is well and easily supplied by lemon-juice, or the citric acid, dissolved in water. The recent herb, eaten as a salad, may be serviceable in scorbutic affections.

1 Gartner de Fructibus, ii. 152. t. 113. fig. 5.

2 This suit is prepared on the Continent by the following process:-The juice is allowed to subside after being slightly heated, and then clarified by adding to it water, in which a small portion of fine clay is suspended. This clarified juice is next boiled till a pellicle forms on its surface, and put aside for a month to crystallize; the operation being repeated until the whole of the salt is obtained, when it is purified by a second crystallization.-Annates de Chimie, xiv. 7. The essential salt of lemon of the shops is generally one half bitartrate of potassa.

3 Crell's Annals, (trans.) i. 107.