(Pentandria Monogynia. _Nat. Ord._ Luridæ _Linn._ Solaneæ _Juss._)
Henbane is an indigenous annual, frequent on waste grounds, and at the sides of roads, particularly on a calcareous soil, flowering in July. The whole of the plant is poisonous when eaten; and in the recent state the odour of the leaves occasions stupor and delirium. The root of this plant when in full vegetation is very powerful; and there are several cases on record, where it has been eaten in mistake for parsnips,[431] which it strongly resembles in its sweet and agreeable flavour. Its operation is very analogous to that of opium; producing sickness, stupor, delirium, and coma, with dilation of the pupils.
The pulse, at first hard, gradually becomes weak and tremulous; petechiæ frequently make their appearance, and death ensues. Late experiments have shewn that a peculiar alkaline body constitutes the active principle of this plant, and it has accordingly received, from its discoverers _MM. Meissner_ and _Brandes_, the name of _Hyoscyama_.
_Boerhaave_ experienced a trembling and drunkenness, in consequence of having prepared a plaister, into whose composition _henbane_ entered as an ingredient; and the experiments of _M. Orfila_ have shewn that it acts nearly in the same manner, whether applied upon the cellular texture, introduced into the stomach, or injected into the veins. Hence it follows that the active principle of this plant is carried into the circulation, and exerts a remarkable action on the brain and nervous system, producing an extraordinary state of delirium, which is succeeded by stupefaction. The physician will never probably be called upon to investigate a case of wilful poisoning by this narcotic; and should he be summoned to attend a person who, through mistake or accident, had swallowed it, we can hardly anticipate any peculiar mystery which requires elucidation.
There are several other species of henbane, as _hyos. alb. aureus_, _physaloides_, all of which are poisonous, although not in the same degree as the _hyoscyamus niger_, whose history we have just considered.
The LAUREL (_Prunus lauro-cerasus_) and its distilled water. BITTER ALMONDS, and their essential oil.
Hydro-cyanic acid exists in a great variety of native combinations in the vegetable kingdom, and imparts to them peculiar qualities, which have been long known. It is, however, only within a few years, that this singular body has been obtained in its separate and independent form[432]; indeed it was not until the publication of the celebrated memoir of _Gay-Lussac_ upon this subject, in the year 1815, that its chemical composition was fully understood. In this memoir, it was clearly shewn to consist of a peculiar, gaseous, and highly inflammable compound of carbon and nitrogen, to which the name of _cyanogene_ has been assigned, and hydrogen; the latter body acting as the acidifying principle; whence the term _hydro-cyanic acid_ is very happily contrived to express its composition.