“False Angostura Bark” contains Strychnia and Brucia, gives a light yellow powder, intensely bitter, and turned red by nitric acid.
Nux Vomica, a flattened circular seed, from half to one inch diameter, generally concavo-convex, with a slight central prominence. Colour greyish-brown; silky from radiating hairs. Substance tough and horny; powder light brown, with an odour like liquorice, and an intense and persistent bitter taste. Nitric acid gives with the powder and with the extract an orange-red colour, owing to the presence of brucia. The aqueous infusion gives a precipitate with tannin, and an olive-green tint with neutral ferric chloride.
Strychnia, C21H22N2O2, occurs in commerce in opaque white rhombic prisms (the “right square octahedra” of the British Pharmacopœia are not met with), inodorous, having a sp. gr. of 1·36. One part of strychnia dissolves in 7000 parts of cold, in 2500 parts of boiling, water; in 1250 parts of ether; in 1000 of carbon disulphide; in 200 of absolute alcohol; in 120 parts of cold, and 10 parts of hot, rectified spirit; in 181 parts of amylic alcohol; in 164 of benzene; and 7 of chloroform. Creasote and essential and fixed oils also dissolve strychnia (Blyth).
It sublimes in needle shaped crystals, or sometimes, if too quickly heated, in drops, at 169° C.; melts at 221° C., finally darkening and carbonizing.
Its bitter taste is its most prominent physical characteristic. I have verified the statement that one grain of strychnia in a gallon (70,000 grains) of water is distinctly perceptible. One grain in 30,000 is markedly bitter.
Its salts are crystallizable, and also bitter, lævo-rotatory in solution, mostly colourless, neutral to test-paper, generally soluble with facility in water, hence more rapidly poisonous than the free alkaloid. Strychnia sulphates occur in large four-sided prisms, octahedrons, or needles, according to the amount of water of crystallization. Strychnia nitrate crystallizes in silky needles, easily soluble in water. The sulphate is officinal in the French, the nitrate in the German, Austrian, Swiss, Norwegian, and Dutch Pharmacopœias. The acetate and hydrochloride are met with in commerce, but are not officinal. Strychnia itself, the free alkaloid, is prescribed in the British Pharmacopœia. Liquor strychniæ is a solution of the hydrochloride.
Separation.—Strychnia is probably the easiest of the alkaloids to detect, on account of its stability and the delicacy of its reactions. One half-millionth of a grain in the pure state is discoverable by the colour tests (Pharm. Journ., July, 1856). Putrefaction does not change it, for Richter detected it in tissues after eleven years (Sammlung Klin. Vorträge, 69, 562), and other observers in decomposed or buried bodies after five to eight weeks. And yet there are few analysts who have not on some occasion failed to find it (see p. 147.) A very small quantity, about a grain, may destroy life. Even of this, only a portion is absorbed; the rest is eliminated by vomiting (when it occurs), and by the urine and fæces; the absorbed portion is diffused with great rapidity through a large mass of blood and tissue; the result is that we are looking for one part of the poison in about a million times its weight of impurities—almost worse than the needle in the haystack. Matters are still more difficult if the theory be true that an alkaloid, in killing, itself suffers change (see pp. 128 and 133)—an idea that Dr. Letheby and Mr. Nunneley strongly repudiated in the Palmer defence, though the latter witness had to admit that he himself had once failed to detect strychnia in an animal to which he had administered it. Dragendorff records several negative results without apparent cause. Taylor (Med. Jur., 1873, Vol. I., 414) mentions cases of non-discovery by Dr. Reese of Philadelphia, Mr. Horsley of Cheltenham, by himself in the organs of an animal hypodermically poisoned; and also a case in which five grains had been taken, and only a little over a grain was found. Sonnenschein (Casper’s Handbook) in one case found a quantity in the stomach, but none in the tissues; yet it had caused death. All these facts greatly support the theory that the alkaloid is itself changed in causing death.
However this be, if the stomach has failed to yield strychnia, the whole of the rest of the organs, the blood, and the muscles—in fact, as much of the body as can be managed—should be extracted with hot redistilled methylated spirit acidified with a little acetic acid. It is easy to fit up an arrangement with a stoneware pan, a wooden cover, and a coil of tin pipe, through which steam can be passed, and thus the alcohol can be kept warm for two or three hours without much loss. Strain the whole through a cloth, distil off most of the alcohol, evaporate on a water bath at about 70° C., and treat the extract as described in the general process for alkaloids. To facilitate the purification, the alcoholic solution may be precipitated by acetate of lead (avoiding much excess), filtered, the lead removed from the filtrate by adding sufficient sulphate of potash in solution and allowing it to settle, and the clear liquid evaporated as before. Much syrupy matter, which occasions trouble, is thus removed.
The ether-chloroform solution (p. 5), by spontaneous evaporation, leaves the strychnia in “rosettes, veined leaves, stellate dotted needles, circles with broken radii, and branched and reticulated forms” (Guy and Ferrier, Forens. Med., 1881, 568). If not yet pure enough to crystallize, advantage may be taken of the fact that while most of the impurities are charred by warm concentrated sulphuric acid, strychnia is very little affected. A few drops of this acid are therefore added to the residue, then it is warmed for ten or fifteen minutes on the water-bath, finally diluted to about ten cubic centimetres, filtered, the filter washed with water, and the filtrate treated again with ammonia and ether-chloroform. The residue left by the latter, on spontaneous evaporation, will now be pure enough for the following
Tests.—1. The microscopic appearances are so various as to be somewhat indefinite; Guy’s description has been already given. If no crystals are found, strychnia and most other alkaloids are unlikely to be present. But if crystals are obtained, they frequently, on further examination, prove to be some inorganic salt or an ammonium compound, leading to wrong conclusions, if the microscope be trusted too much.