Conium maculatum. Poison-Hemlock.

Nat. Ord. — Apiaceae. Sex. Syst. — Pentandria Digynia.

Leaves and Seeds.

Description. — Poison Hemlock, or Poison Parsley, as it is sometimes called, is an umbelliferous plant, having a biennial, fusiform, whitish, fleshy root, and a herbaceous, branching stem, from three to six feet high, erect, round, hollow, smooth, shining, glaucous, slightly striated, and copiously marked with brownish-purple spots. The leaves are tripinnate ; the lower ones very large, and attached to the joints of the stem by sheathing petioles ; the upper are smaller, and inserted at the divisions of the branches ; both have channeled footstalks. The leaflets are ovate, closely and sharply pinnatifid, with the lower lobes incised, deep-green on their upper surface and paler beneath. The flowers are numerous, small, white, all fertile, the outermost very slightly irregular, they are arranged in erect, terminal, compound, many-rayed and smooth umbels. General involucre ovate, cuspidate, with membranous edges, consisting of from three to seven lanceolate, reflected bracts, with whitish edges ; partial involucre of three or four, oval, pointed, spreading bracts, and with the inner side wanting. Petals obcordate, with acute, inflected points, and five in number. The fruit is about a line and a half, or rather less in length, by a line in breadth, roundish-ovate, compressed, of a pale-green color ; primary ridges elevated, sharp, undulated ; commissures and channels finely wrinkled. The whole plant has a disagreeable, virose smell, which is more powerful when it is bruised or broken.

History. — Hemlock is a native of Europe and Asia, and is naturalized in many parts of the United States. It flowers in June and July. The leaves and seeds are the officinal parts. The proper time for collecting the leaves is when the flowers begin to fade ; the footstalks should be rejected, and the leaflets dried quickly, and kept excluded as much as possible from the light and air. The fruit, commonly called seeds, retains its activity much longer than the leaves.

Dried hemlock leaves are of a dark-green color, and have a strong, heavy, narcotic odor, and a nauseous and bitterish taste. The seeds have a yellowish-gray color, a feeble odor, and a somewhat bitterish taste. Alcohol or ether takes up the medicinal properties, and the ethereal extract, which is of a rich, dark-green color, possesses the full virtues of the plant, producing headache and vertigo in a half grain dose. The aqueous extract is uncertain ; the alcoholic extract is the best. There has been no satisfactory analysis of this plant, a volatile oil, albumen, resin, coloring matter, a poisonous oil, conia, and salts, have been found in it. The poisonous empyreumatic oil is obtained by destructive distillation of the leaves. A volatile, alkaline principle termed Conia or Conicine, is the active agent of the plant ; it may be obtained by cautiously distilling from a muriate of lime bath, a mixture of strong solution of potassa -with the alcoholic extract of the unripe fruit. The alkaloid passes over into the receiver with the water, and floats upon it like an oil. Or, the full grown, but still green fruit, may be distilled with water, caustic potassa, and slaked lime, from a muriate of lime bath, then neutralize the distilled fluid with sulphuric acid, and concentrate it by evaporation to the consistence of syrup ; act on this with a mixture of two parts of rectified alcohol and one of sulphuric ether, and again obtain an extract by evaporation, and finally distil the extract with a strong solution of caustic potassa. As obtained in either of these ways, conia contains, — some water, which may be removed by chloride of calcium, — and also a little ammonia which is separated by exposing it under an exhausted receiver till it ceases to emit bubbles of gas. In the preparation of conia, the fresh leaves or seeds should always be employed, as the alkali undergoes decomposition, by time and exposure. The seeds contain the most of it. Eight pounds of green fruit or seeds, will yield half an ounce of hydrate of conia.

Conia is a yellowish, oily liquid, lighter than water, colorless at first, but becoming brown by oxidation, of an intense, peculiar, suffocating odor, like the urine of mice, and an extremely acrid, benumbing taste. Its density is .878 ; it is volatile at ordinary temperatures, disengaging ammonia, and depositing a resinous matter, and loses its activity. It is sparingly soluble in water; but forms a hydrate by uniting with about a fourth part of water. It is very soluble in alcohol, ether, the fixed and volatile oils, and also in weak acids, which it neutralizes. It boils at 370°, and distils over with water at 212°. It strongly blues reddened litmus paper; it forms soluble salts with acids which are difficult to crystallize. Weak tincture of iodine yields a white precipitate, which acquires an olive color with an excess of the tincture. Tannic acid gives a white, insoluble precipitate ; corrosive sublimate gives a white precipitate ; chloride of zinc gives a white gelatinous precipitate, soluble in excess of the conia. Sulphate of sesquioxide of iron and chloride of platinum yield yellow precipitates ; chloride of gold a light yellow. Chloride of cobalt yields a blue precipitate which changes to green, and which forms with ammonia a red solution. Acetate of copper gives a gelatinous blue precipitate. The red permanganate of potassa is immediately decolorized. Hydrochloric acid yields white clouds as ammonia does, and renders it violet, especially when heated. Nitric acid imparts to it a topaz color, unchanged by heat. Pure and concentrated sulphuric acid does not alter it ; but if heated produces a greenish-brown color, which becomes blood-red, and finally black, if the heat be continued. It coagulates albumen, and precipitates the salts of copper, lead, zinc, aluminum, manganese, and iron. It also precipitates nitrate of silver, but in excess redissolves the precipitate. Its salts are mostly decomposed by evaporation. The actions of conia upon the system closely resemble those of the hemlock itself. A drop of it injected into the eye of a rabbit, caused death in nine minutes, and three drops killed a strong cat in a minute and a half; its effects are gradual paralysis, slight convulsive tremors, and death from suspension of the breathing, without any change in the appearance of the blood, and without any depression of the heart's action. It acts on the spinal marrow. It consists of carbon, hydrogen, and nitrogen. (N C₁₇ H₁₇.)

Properties and Uses. — Narcotic. When given in doses sufficient to affect the system, it causes more or less vertigo, dimness of vision, nausea, faintness, sensations of numbness, and general muscular debility. In larger doses it occasions dilated pupils, difficulty of speech, delirium, or stupor, tremors and paralysis, and frequently convulsions and even death. Its operation usually commences in less than half an hour, and continues for from twelve to thirty-six hours. It is supposed to effect its results by exhausting the nervous energy of the spinal cord, and voluntary muscles. It is used for promoting sleep, and will be found extremely useful in allaying excessive action of the heart in hypertrophy of this organ ; a pill of one or two grains of the extract producing a calm, soothing influence, followed by a diminution or removal of the palpitation or augmented action. Indeed, all affections attended with an excited or excitable condition of the nervous and vascular systems, will be benefited by its use. I have used a preparation which I call the Conium Mixture, with much advantage in several diseases ; it is prepared as follows : Take of Precipitated Carbonate of Iron ten drachms ; inspissated juice of Conium five drachms ; Tincture of Balsam Tolu six ounces; Oils of Cinnamon and Wintergreen, of each twelve drops; White Sugar two ounces ; Madeira Wine, Water, of each half a pint. Mix together, in a week the mixture will be ready for use. In dyspepsia attended with irritation of the stomach, pyrosis, or with an excitable state of the system from debility, this mixture will be found very beneficial ; it may be given in doses of from a drachm to half an ounce, from three to six times a day before eating. Laxatives should be occasionally employed. In cough, conium will be found of much utility ; I have used the following preparation in the cough attending phthisis, also in other coughs, with benefit : Take of Tincture of Cyanuret of Potassium, (made by adding twenty-two grains of the Cyanuret to nine fluidounces of Proof Alcohol,) six drachms ; Conium Mixture three ounces ; Tincture of Opium four drachms. Mix. Dose half a drachm to a drachm, three or four times a day. In intermittent fever I have frequently derived a happy effect from the following pill, when quinia alone failed ; Take of sulphate of quinia ten grains; inspissated juice of conium fifteen grains. Mix, and divide into twenty pills, of which one pill may be given every hour or two, until the effects of the conium have commenced, after which give one pill every four or five hours, according to its influence. In consequence of the action of conium on the spinal marrow it lessens the venereal appetite. It likewise lessens the secretion of milk. In the neuralgic pains attending carcinomatous affections it usually gives relief ; sometimes, however, it has exerted no influence whatever, in palliating them. In scrofula, goitre, and indeed in all tuberculous affections, it will be found very effectual given in combination with the iodide of iron. It enters into the Compound Plaster of Belladonna, an excellent preparation, which I have been in the habit of using for many years. The leaves have likewise been employed externally as a poultice to painful tumors, ulcers, neuralgic and rheumatic pains, etc. The aqueous extract of this plant is worthless ; the inspissated juice, or the ethereal extract, are alone valuable. A strong solution of the inspissated juice, or the juice of the fresh leaves, coated over the parts daily, for five or six days, will cure the itch. Dose of the leaves and inspissated juice, from one to three grains, three or four times a day ; of the ethereal extract, which is an elegant extract of a rich dark-green color, from one-eighth of a grain to one-half of a grain. Conia, the active principle, is not used in medicine.

The Cicuta Maculata, Water Hemlock, is seldom used, being superseded by the Conium, which is deemed the safer article.

Off. Prep. — Extractum Conii Alcoholicum ; Emplastrum Belladonnae Compositum ; Unguentum Conii.

The American Eclectic Dispensatory, 1854, was written by John King, M. D.