The crude oil is brownish-yellow, and very sparingly soluble in water, one part requiring more than 600 times its weight for complete solution. It does not contain sulphur, as previously asserted by Payen and Chevallier, nor does it reduce ammoniacal solution of silver. Oxidation by nitric acid produces valerianic acid and a yellow acid resin; if dropped on melted caustic potash, valerianate, carbonate of potash, and a hydrocarbon are the results. The oil appears to be neither narcotic nor poisonous, twenty drops having had no action whatever on a kitten (W. Keil); but the wonderful preservative properties ascribed to it by older writers are very problematical.

The ash of the hop differs but little from the ashes of foliar organs generally, the relative proportion of each constituent varying within somewhat wide limits, according to the particular variety. (See accompanying table.)

A few other bitter principles, some of which have actually been found, and the remainder are supposed to exist, may be now conveniently described. (For Picrotoxin and Colchicine the reader is referred to the author's work on "Poisons.")*

§ 259. Absynthin, C40H28OHO.—The bitter principle of wormwood, Artemisia absinthium. It may be extracted from the hot aqueous extract of wormwood by precipitation with tannic acid, evaporating the tannate to dryness with oxide of lead, and extracting the dried residue by alcohol, and subsequent purification with animal charcoal. Absynthin dissolves easily in alcohol and ether, with difficulty in hot water, and is scarcely soluble in cold. When obtained from alcoholic solution it is usually in the form of pale-yellow drops, which gradually become crystalline; it has a peculiar odour and extremely bitter taste, and its reaction is neutral. It reduces a hot ammoniacal solution of silver nitrate, but an alkaline tartrate of copper solution remains unchanged by it. It is dissolved by caustic potash with the production of a brown colour. Concentrated sulphuric acid produces first a brown colour, passing into a green-blue; as water is added, the colour becomes darker, until grey flocculent particles are separated. Boiling with dilute acids produces resinous products,

but no sugar.

The bitter principle, according to some observers, is a direct cerebral excitant; according to others, a pure tonic. It is used occasionally in medicine, in doses from grain to 2 grains, and the herb producing it is officinal in the Continental pharmacopœias.t

15

17

$260. Aloin-C16H1807 (TILDEN), CH180, (STENHOUSE), C16H1607 (E. SCHMIDT)—may be obtained by treating aloes with dilute sulphuric acid, removing the deposit of resin, and evaporating to a syrup. The crystals thus obtained are yellow needles, soluble in water and alcohol, and possessing a bitter taste. The amount of crystallisation water varies from 5.89 to 14.29 per

Bibliography.

LERMER-Dingl. Polytech. Journ., clxix. 54; Viertelj. Pract. Pharm., xii. 505.

PEREIRA'S "Materia Medica."

HUSEMANN. "Die Pflanzenstoffe," &c.

PAYEN and CHEVALLIER.-Journ. Pharm., [2], viii. 214, 533.

PERSONNE.-Journ. Pharm., [3], xxvj. 22, 241, 329.

KROMAYER.-Arch. Pharm., [3], cviii. 129.

LEONARDI.-Osservazioni ed esperienze del Dott. Lupis sopra la virtù

antifebrile dell estratto amarissimo d'assenzio, &c. Milano, 1828. LUCK.--Ann. Chem. Pharm., liv. 112; lxxviii. 87.

RIGHINI. Journ. Chim. Méd., 2e ser., ix. 383.

cent.; if anhydrous, the melting point of the crystals is from 70° to 80° [146° to 148°F.]; if hydrous, sulphuric acid colours it first red, then orange, and it is dissolved by caustic potash with the production of a purple-red colour. The action of nitric acid produces chrysammic, picric, and oxalic acids, with the addition of carbonic anhydride; that of zinc dust, methylanthracene and anthraquinone

§ 261. Cnicin, C42H56015, was discovered by Nativelle in the leaves of the Cnicus benedictus; it is found also in the Centaurea calcitrapa, and in other composite plants. It forms transparent silky crystals, neutral, without smell, of very bitter taste, melting at a high temperature, but not subliming. Its solution turns the plane of polarisation to the right [a] r = 130°68. It is scarcely soluble in cold water, more so in boiling, soluble in all proportions in alcohol and wood spirit, almost insoluble in ether. Cold sulphuric acid gives with enicin a red solution, becoming violet on the addition of water, and yellow on the addition of ammonia. Cold concentrated hydrochloric acid dissolves it with the production of a green colour; on heating, brown drops separate, which solidify into a yellow resin.†

§ 262. Daphnin, C3H8O19, a crystalline principle discovered by Vauquelin, 1817, in the bark of the Daphne alpina, L., and D. mezereum, L. It forms long rectangular prisms, or fine needles, and crystallises with four atoms of water. Its reaction is neutral, its taste bitter. When anhydrous it melts at about 200° to a colourless fluid, which again becomes crystalline on cooling; if the heat is continued, it sublimes as daphnetin, C19H1409. This substance presents itself in fine, colourless, rhombic prisms, melt*Bibliography.

GROVES.-Pharm. Journ. Trans., xvj. 128 ; Journ. Pharm., [3], xxxi. 367.
FLUCKIGER. "Year-Book of Pharmacy," 1872.
HANBURY and FLUCKIGer.

1

Pharmacographia," 1876.

KOSMANN.-Journ. Pharm., [3], xl. 177; Bull. Soc. Chim., v. 530.
ORLOWSKY.-Zeitsch, analyt. Chem., v. 309.

ROBIQUET.-Journ. Pharm., [3], x. 173; xxix. 241.

ROCHLEDER and CZUMPELIK.-Wien. Akad. Ber., xliv. [2], 493; xlvii. [2], 119.

SCHMIDT.-Arch. Pharm. [3], vi. 496-509.

SCHROFF.-N. Repert. Pharm., ii. 49.

SMITH, T. and H.-Chem. Gaz., 1851, 107; Journ. Pharm. [3], xix. 275. STENHOUSE.-Phil. Mag. Journ., xxxvij. 481; Ann. Chem. Pharm., lxxvij. 208.

TILDEN:-Pharm. Journ. Trans., [3], vj. 208-210.

+ BOUCHARDAT.-Compt. Rend., xviii. 299.

DESSAIGNES and CHAUTARD. -Journ. Pharm., [3], xxi. 26.

HUSEMANN.. Die Pflanzenstoffe."

--

Berlin, 1871.

NATIVELLE.-Journ. Chim. Méd., xxi. 69.
SCRIBE.-Compt. Rend., xv. 802.

ing about 250°; it has a bitter taste, with a weak acid reaction, and is easily soluble in boiling water, with the production of a yellow colour; it dissolves also in boiling alcohol, but is very little soluble in ether.

Daphnin dissolves slightly in cold water, easily in hot; it is also very soluble in hot alcohol, but is not dissolved at all by ether. In solutions of the caustic and the carbonated alkalies it dissolves with the production of a yellow colour, and is also easily soluble in acetic acid. On boiling with a dilute acid, daphnin breaks up into daphnetin and sugar, and emulsin and fermentation with yeast have a similar effect. An aqueous solution of chloride of iron produces, when cold, a blue colour, and if the liquid is boiled, a dark yellow precipitate. Nitric acid colours

it red.*

§ 263. Gentianin, C1H10O5, discovered by Henry and Caventou in 1821, but first prepared pure by Trommsdorff, is found, like gentiopicrin, in the root of the Gentiana lutea, L. It forms long, pale-yellow, silky needles, without smell or taste, which may be sublimed above 300° without decomposition. Its solubility, according to Leconte, is as follows:-1 part requires of cold water 5000 parts, of boiling 3850 parts; of cold absolute alcohol 455 parts, of boiling 62.5 parts; of cold ether 2000 parts, for solution. Concentrated sulphuric acid dissolves it with a yellow colour; on dilution with water it separates unchanged; on being boiled with dilute sulphuric acid there is no change. If treated with pure nitric acid (1·43 specific gravity), a dark-green solution is obtained, and on adding water carefully dinitrogentianin, CHg(NO2)2O5 + H2O separates out as a green powder. If similarly treated with strong nitric acid, and subsequent addition of water to the solution, yellow microscopical prisms are separated, probably trinitro-gentianin. Gentianin reduces nitrate of silver.†

§ 264. Gentiopicrin, C20H30012, first prepared pure by Kromayer in 1862, is a glucoside found in the fresh root of the Gentiana lutea. It crystallises in colourless needles, with one atom of water

ROCHLEDER.-Journ. Pract. Chem., xc. 442.

VAUQUELIN.-Ann. Chim., lxxxiv. 174.

ZWENGER.-Ann. Chem. Pharm., cxv. 1.

BAUMERT.-Ann. Chem. Pharm., lxii. 106.

HENRY and CAVENTOU.-Journ. Pharm. [2], vij. 173.
HUSEMANN. "Die Pflanzenstoffe." Berlin 1871.

LECONTE.-Journ. Pharm., [2], xxiii. 465.

TROMMSDORFF.-Ann. Chem. Pharm., xxi. 134.

of crystallisation. The crystals effloresce in the air, and lose their transparency, becoming white and opaque. The anhydrous crystals melt between 120° and 125° to a brown fluid, which coagulates amorphously, and at higher temperatures is fully destroyed. Water dissolves it easily, but it is insoluble in absolute alcohol and in ether, though, on the other hand, weak alcohol is an excellent solvent for it. One of the best tests for its presence is the action of concentrated sulphuric acid, giving in the cold a colourless solution, but producing with slight warming a carmine-red colour, and precipitating on the addition of water in grey flocks. It reduces an ammoniacal solution of silver nitrate, and in boiling with dilute sulphuric acid splits up into sugar and gentiogenin.

Gentiogenin, CH1605, is an amorphous, yellow-brown powder, of neutral reaction and bitter taste, not easily soluble in cold water, but dissolving readily in alcohol and ether.*

$265. Menyanthin, C30H4604, a glucoside obtained pure by Ludwig and Kromayer in 1861, from the Menyanthes trifoliata, L. As hitherto prepared, menyanthin is an amorphous, terebinthinate mass, becoming slowly solid on drying over sulphuric acid. It has a neutral reaction, and its taste is strongly and purely bitter. It softens at 60° to 65°, and melts at 10° to 15° to a thin, clear fluid, which again solidifies to a hard transparent mass; by stronger heating it is entirely destroyed. Concentrated sulphuric acid gives with it a yellow-brown colour, which on standing becomes violet-red, and grey flocks are separated on the addition of water. By heating with dilute sulphuric acid it splits up into sugar and menyanthol.

Menyanthol is an oil having an acid reaction, and an odour like that of oil of almonds; it is changed by the air (as well as by melting with potash) into a crystalline acid capable of being sublimed.t

§ 266. Quassiin, C10H12O3, a bitter principle, discovered in 1835 by Winckler, in the bark of the Quassia amara, L., and Picræna excelsa, L. It forms white, opaque, glittering crystals, without odour, and of extremely bitter taste. On heating, it melts and solidifies as a transparent yellow mass; at decomposition temperatures it burns like resin, if exposed to the air. Tannic acid precipitates it from an alcoholic solution in thick, white flocks;

Bibliography.

HUSEMANN. "Die Pflanzenstoffe."

KROMAYER.-Arch. Pharm. [2], cx. 27.

+ HUSEMANN.-Die Pflanzenstoffe. Berlin, 1871.

KROMAYER.-Arch. Pharm. [2], cxxiv. 37.

LUDWIG and KROMAYER.—Arch. Pharm. [2], cviii. 263.