Hyoscyamine is easily decomposed by caustic alkalis. By boiling with baryta in aqueous solution, it is split into Hyoscine, C₆H₁₃N, and Hyoscinic Acid, C₉H₁₀O₃. The former is a volatile oily liquid of a narcotic odour and alkaline reaction. By keeping it over sulphuric acid it crystallizes and also yields crystallized salts; hyoscine may be closely allied to conine, C₈H₁₅N. Hyoscinic acid, a crystallizable substance having an odour resembling that of empyreumatic benzoic acid.[1703] It melts, according to Höhn, at 105°; tropic acid ([see p. 457]), melting at 118°, agrees so very nearly with hyoscinic acid that further researches will probably prove these acids to be identical.
Another process for extracting hyoscyamine is due (1875) to Thibaut. He removes by bisulphide of carbon the fatty oil from the powdered seeds, and exhausts them with alcohol slightly acidulated by tartaric acid. The alcohol being distilled off, the author precipitates the alkaloid by means of a solution containing 6 per cent. of iodide of potassium and 3 per cent. iodine. By decomposing the precipitate with sulphurous acid, hydroiodic acid and sulphate of hyoscyamine are formed. The latter is dried up at 35° with magnesia and the hyoscyamine extracted by alcohol or chloroform. The crystals melt at 90°. Thibaut found the alkaloid thus prepared from seeds differing from that yielded by the leaves, the latter having a somewhat strong odour.
Attfield[1704] has pointed out that extract of henbane is rich in nitrate of potassium and other inorganic salts. In the leaves, the amount of nitrate is, according to Thorey,[1705] largest before flowering, and the same observation applies to hyoscyamine.
Uses—Henbane in the form of tincture or extract is administered as a sedative, anodyne or hypnotic. The impropriety of giving it in conjunction with free potash or soda, which render it perfectly inert, has been demonstrated by the experiments of Garrod.[1706] Hyoscyamine, like atropine, powerfully dilates the pupil of the eye.
Substitutes—Hyoscyamus albus L., a more slender plant than H. niger L., with stalked leaves and bracts, a native of the Mediterranean region, is sometimes used in the south of Europe as medicinal henbane. H. insanus Stocks, a plant of Beluchistan, is mentioned in the Pharmacopœia of India as of considerable virulence, and sometimes used for smoking.
FOLIA TABACI.
Herba Nicotianæ; Tobacco; F. Tabac; G. Tabakblätter.
Botanical Origin—Nicotiana Tabacum L.—The common Tobacco plant is a native of the New World, though not now known in a wild state. Its cultivation is carried on in most temperate and subtropical countries.
History—It is stated by C. Ph. von Martius[1707] that the practice of smoking tobacco has been widely diffused from time immemorial among the natives of South America, as well as among the inhabitants of the valley of the Mississippi as far north as the plant can be cultivated.
The Spaniards became acquainted with tobacco when they landed in Cuba in 1492, and on their return introduced it into Europe for the sake of its medicinal properties. The custom of inhaling the smoke of the herb was learnt from the Indians, and by the end of the 16th century had become generally known throughout Spain and Portugal, whence it passed into the rest of Europe, and into Turkey, Egypt, and India, notwithstanding that it was opposed by the severest enactments both of Christian and Mahommedan governments. It is commonly believed that the practice of smoking tobacco was much promoted in England, as well as in the north of Europe generally, by the example of Sir Walter Raleigh and his companions.