Citrus medica, var. Limonum, (Risso) Hooker filius.

The outer rind of the fresh ripe fruit.

Habitat. N. India; cultivated in subtropics, Mediterranean Basin, United States (California, Florida),Australia, etc.

Syn. Limon. Cort.; Fr. Ecorce (Zest) de Citron (Limon); Citron, Limon; Ger. Cortex Fructus, Citri, Flavido Corticis Citri, Citronen Limonen)-schale; Limone, Citrone.

Med'i-ca. L. medicus, medical, curative - i. e., properties useful in medicine.

Li-mon'um. L. a lemon, fr. Arab, limun, limu, taken from Skr. nimbuka.

Plant. - Straggling bush of tree, 3-4.5 M. (10-15°) high, more tender than the orange, having many angular branches and sharp spines in the leaf-axils; bark gray, that of branches green, of twigs

Fig. 226.   Citrus medica, var. Limonum: a, flower; b, fruit.

Fig. 226. - Citrus medica, var. Limonum: a, flower; b, fruit.

reddish or purple; leaves evergreen, 5-6 Cm. (2-2 2/5') long, ovate, acute, serrate, 12 Mm. (1/2') petioles; flowers all the year round, sweet-scented, white to purplish-pink; fruit ovoid berry 7.5 Cm. (3') long with nipple-shaped extremity, smooth, depressed punctations over the oil-glands, structure like orange; pulp acid, yellow; seeds as in orange, only smaller. Peel, the outer, lemon-yellow, dark yellow layer, recently separated by grating, paring, and consisting of an epidermal layer, numerous parenchyma cells containing yellow chromoplastids, and large oil reservoirs with globules of the volatile oil; odor highly fragrant, distinctive; taste pungent, aromatic; microscopically - sections mounted in a fixed oil show epidermal layer (small tabular cells), hypodermal layer containing numerous plastids, a mesocarp with colorless, thin-walled parenchyma, large elliptical oil reservoirs, granular protoplasm, calcium oxalate crystals. The inner spongy white portion should be removed and discarded. Solvents: alcohol; wine; water. Dose, 3ss-l (2-4 Gm.).

Commercial. - Lemons reach us from California, Florida, W. Indies, Mediterranean region (Sicily, Spain, etc.) packed in boxes, each lemon being wrapped in white or brownish tissue-paper. Foreign varieties are known as wax, imperial, gata, and all, when kept several months, deteriorate, owing to the decomposition of citric acid, into sugar and carbon dioxide, in consequence of which, to insure preservation and permit long shipments, they must be coated with melted paraffin, dissolved shellac, or varnish. The rind should be pared thinly from the fruit with sharp knives and carefully dried.

Constituents. - Volatile oil, bitter principle, hesperidin, ash 4 p. c.

Oleum Limonis. Oil of Lemon, official. - (Syn., 01. Limon., Lemon Oil, Oleum de Cedro; Fr. Essence (Huile) de Citron - Cedrat; Ger. Citronol, Limonenol.) This volatile oil is produced mostly in Sicily, S. France, Italy (Calabria), by expression from fresh peel of the ripe fruit, using several processes that rupture mechanically the oil-cells thereby liberating the oil and rendering it easily collected: 1, spugna - collecting by sponge the oil from ruptured cells of the quartered rind; 2, scorzetta - of the halved rind; 3, machina - substituting a complicated machine for manual labor of expression and collection; 4, ecuelle a piquer - not much used but consisting of an instrument, bowl-shaped, 25 Cm. (10') wide, of tinned-copper, having a raised opening in the centre which forms with the outer edge a broad channel; to this there is a heavy cover similarly shaped, whose inner surface as well as that of the machine is armed with concentric rows of short 6 Mm. (1/4') spikes or ridges; an opening in the bottom allows the escape of oil. By a handle the cover is made to revolve rapidly one-half minute over the instrument, having between the two 5 to 8 fruits, after which they are replaced by fresh ones. About 7000 fruits can be exhausted daily by each machine. It is a pale yellow, greenish-yellow liquid, characteristic odor and taste of lemon, sp. gr. 0.853, dextrorotatory, soluble in 3 vols. of alcohol; contains at least 4 p. c. (7-8) of aldehydes calculated as citral, C10H16O, which gives the aroma and value (being also produced by oxidizing geraniol, C10H18O, with chromic acid), limonene (citrene), C10H16, 76 p. c, little cymene, C10H14, citronellal, C10H18O, phellandrene, pinene, geranyl acetate, a sesquiterpene, octyl aldehyde, nonyl aldehyde, methyl heptenone, terpineol. Should be kept cool, dark, in well-stoppered, amber-colored bottles, and that having a terebin-thinate odor must not be dispensed. Dose, ej-5 (.06-.3 Ml. (Cc.)).

Adulterations. - Oils of other Citrus fruits, fixed oils, alcohol, oil of turpentine. The fragrant Oil of Petit Grain Citronnier, from immature fruits, leaves, and twigs, closely resembles Neroli Petit Grain, and may be used similarly.

Hesperidin, C22H26O12. - A glucoside (bitter principle) from the white, spongy part or rind by boiling water; bitter, yellowish-white powder or white needles; soluble in diluted alkalies or acetic acid, black 23 with ferric salts, and by diluted sulphuric acid decomposed into hes-peretin, C16H14O6, and glucose, C6H12O6.

Preparations. - I. Peel: 1. Tinctura Limonis Corticis. Tincture of Lemon Peel. (Syn., Tr. Limon. Cort.; Fr. Teinture d'Ecorce de Citron; Ger. Citronenschalentinktur.)

Manufacture: 50 p. c. Similar to Tinctura Aloes, page 110 - macerating lemon peel 50 Gm. in alcohol 100 Ml. (Cc), finishing with alcohol q. s. 100 Ml. (Cc), filter through purified cotton. Dose, 5ss-2 (2-8 Ml. (Cc.)).

Prep.: 1. Syrupus Acidi Citrici, 1 p. c.

II. Oil: 1. Spiritus Ammonioe Aromaticus, 1 p. c. 2. Spiritus Aurantii Compositus, 5 p. c.

Unoff. Preps.: I. Peel: Spirit, 5 p. c, + oil 5 p. c. (alcohol), dose, 3ss-2 (2-8 Ml. (Cc.)). Infusum. Syrup. Juice (from fruit - used alone, neutralized by alkali, or made into syrup; soon spoils, but will keep a short time by lettings tand until albumin is coagulated, straining into hot bottles, and covering with almond or sweet oil; flavor is preserved best by making it into concentrated syrup); yield 1/2-1 ounce (15-30 Ml. (Cc.)) per lemon, dose, 3ij-5 (8-20 Ml. (Cc.)).

Properties and Uses. - Stimulant, stomachic, added usually to infusions, tinctures, etc., chiefly for flavoring. Juice refrigerant, relieves thirst, febrile inflammatory affections in agreeable beverages; diaphoretic (neutral mixture), scurvy (seamen on long voyages should take ℥j (30 Ml. (Cc.)) daily as a preventive), acute rheumatism; locally in sunburn, pruritus of scrotum, uterine hemorrhage after labor, gargle in diphtheria.

Limones, Lemons. The fruit, official 1830-1860. Limonis Succus, Lemon Juice, official 1860-1910.

Allied Plants:

1. Citrus Aurantium, var. Bergam'ia, Bergamot. - Volatile oil, from rind of fresh fruit, official 1840-1900; S. Italy, France; cultivated. Small tree resembling the lemon and orange, flowers peculiar, delicious odor, fruit pale lemon color, pyriform or globose, with concave receptacles of oil in the rind. Oil obtained as that of lemon and orange, and is a greenish, thin liquid, peculiar fragrant odor, aromatic bitter taste; contains limonene (citrene), dipentene (bergaptene, bergamot camphor), linalool, and linalool acetate 36-39 p. c, upon which the value chiefly depends. Stimulant, excitant, aromatic; used exclusively as a perfume.

2. C. med'ica, Citron. - Small tree, but fruit very large, 20-22.5 Cm. (8-90 long, resembling pineapple in shape. The rind is popular as a dessert, essence in perfumery, and juice for similar purposes as that of lemon and lime fruits. C. medica, var. acida. Succus Citri, Lime Juice; contains citric acid 5-10 p. c. Succus Citri et Pepsinum, lime juice 60 p. c, + glycerite of pepsin 40.