NUX VOIWICA, ALKALOIDS OF, The beans and hark of the nux vomica, and of several other species of the genus strychnos [SrnYcnNos, in NAT. HIST. Div.] contain three alkaloids, namely, (I) strychnine, (2) brucine, (3) igasurine. It is to these alkaloids that the poisonous properties of the plants are due. Iu the beans of the strychnos nux tomica the alkaloids exist in combination with igumtric acid, but in the bark chiefly with gallic acid..
(1). Strychnine. Vauqueline, Tetanine. This alkaloid was discovered by Pelletier and Caventou in 1818. Several processes for extracting it from nux vomica have been described, hut the follow ing by Mr. Horsley is, perhaps, the 'most convenient yet published. An acetic extract is first made by kneading up the nux vomica powder with its own weight of commercial acetic acid ; this is thinned out with five or six times its bulk of water, and the whole allowed to digest for a few days. The clear liquor must then be decanted off, and an equal quantity of fresh water poured on the nines and allowed to digest for a day or two longer, or till all soluble matter is extracted ; the clear liquor is then decanted, mixed with the former liquor, and the whole evaporated, to a syrupy consistence. When the resulting solu tion is cold, dilute with an equal bulk of water, add excess of liquid ammonia, and set by for a day or two that the strychnine may crystal.
use out. Next pass through a calico filter to separate the dark green mother liquor, and digest the resinoid residuum in hot dilute acetic acid and filter. The strychnine and brucine may now be precipitated by solution of potash, or the strychnine only by the addition of solu tion of chromate of potash, when a chromate of strychnine will be obtained free from brucine, provided the liquid, which retains the brucine, be tolerably acid. Chromic acid may be readily separated from the strychnine by digesting the ohromate of strychnine in ammonia, when the alkaloid is left in a state of snowy whiteness. • The amount of strychnine present in nux vomica, St. Ignatius beans, and other derivatives of the strychnos tribe, varies from five-tenths to one and a half per cent.
Strychnine is colourless and inodorous, but of intensely bitter taste, one part in one million of water possessing decided bitterness. Its crystalline form is octohedral, or square prismatic. It is only slightly soluble in water, one part requiring seven thousand parts of cold water, or nearly three thousand parts of hot water, for its solution ; in round numbers one grain of strychnine is soluble in one pint of cold water.
It is insoluble in absolute alcohol, pure ether, or alkaline solutions ; but soluble in the essential oils, chloroform, and ordinary alcohol.
Strychnine exerts lwvo-rotation on a polarised ray, with double the power of brucine. It fuses when heated, but is not sublimeable. Dis tilled with hydrate of potash it furnishes quinoline.
Strychnine is an exceedingly powerful poison, and has of late years been much used for criminal purposes. A great deal of attention has
consequently been bestowed upon it by chemists, and its detection in the various parts of an animal that has been killed by it is now as certain and as easy as that of any of the well-known mineral poisons.
The following process by Messrs. Rodgers and Girdwood is one of several, but is perhaps more convenient than some others :—The sub stance operated upon is digested with dilute hydrochloric acid, one to ten, until it is apparently fluid ; the liquid is then filtered and evaporated to dryness over a water-bath, treated with spirit as long as anything is dissolved, the filtered tincture evaporated as before, and the residue treated with water and filtered; this aqueous solution must now be rendered alkaline by ammonia, and agitated in a bottle, or long tube, with about half an ounce of chloroform ; after subsidence the chloro form is drawn off by means of a pipette, transferred to an evaporating basin, and the chloroform expelled over a water-bath ; the residue must then be moistened with concentrated sulphuric acid, and exposed for some hours to the temperature of a water-bath, by which proceeding all organic matter except the strychnine is destroyed. The charred mass is then treated with water, and the solution filtered to separate the carbon ; excess of ammonia is now added, and the solution again agitated with about, one drachm of chloroform ; if on evaporating a small portion of this chloroform solution, and treating the residue with concentrated sulphuric acid, any charring takes place, the preceding process must be repeated until the strychnine from the chloroform solution remains in a perfectly pure state. 'Pure strychnine, obtained as just described, or in any other manner, is at once recognised by the following reactions :—The first is known as the colour test, and consists in evaporating to dryness a solution of a fragment of the alkaloid on a white plate, and then allowing to flow over it a small quantity of sulphuric acid previously slightly coloured with bichrotnate, or red e-ussiate, of potash ; on coming into contact, a beautiful violet colour, fading into a rose-red, is produced, if any quantity greater than the one-thousandth of a grain of strychnine is present. Some other oxidising agents produce the same effect. A solution of strychnine also gives characteristic precipitates with tannic acid, terchloride of gold, chromate or bichromats of potash, carbazotic acid, iodine, &c., but these should all be confirmed by the application of the colour test. The physiological test recommended by Marshall Hall, consists in placing frogs in the suspected solution, or injecting small quantities of the fluid into the thoracic or abdominal cavity. when tetanic convulsions will ensue if strychnine be press nt. Strychnine is a powerful base; it precipitates most metallic oxides from their salts, and combines with acids to form a well-marked aeries of compounds, many of which have been described by Abel and Nicholson.