NICOTIA'NA TAIIRC UM, an annual plant, of which the leaves are used in a variety of forms and ways, and also in medicine. The dried leaven are large, long, entire, smooth, somewhat glutinous, and of a brown colour, with a peculiar stupifying odour, and an acrid, nauseous, bitter taste. The processes of maceration and partial fermentation, and admixture of different substances, render it inure agreeable in tho dried than in the fresh state. The analysis of tobacco shows its chief ingredients to he :-1st, a tobacco-camphor, called nicotian, or nico tianin, which crystallises, and is solid at the ordinary temperature of the air ; has a faint odour of tobacco, with a warm, bitterish aromatic, but not acrid taste, and is not possessed of any narcotic power; if applied to the nostrils, it causes sneezing ; and if a grain be taken into the stomach, it creates uneasiness and giddiness. It is called by some the acid principle of tobacco, and if such be its nature, it is most probably combined in the herb with, 2nd, nicotine, an alkaloid, which, bke couie, does not exist at ordinary temperatures in a solid form, but in a fluid and volatile state, having an oily appearance.
The empyreuniatic oil of tobacco appears to be formed during the destructive combustion, and does not exist naturally in the leaf, but is probably formed at the expense of the nicotine. It does not therefore exist in the infusion of tobacco, the mode of action of which differs in several respects from the other forms in which it is employed. The products of tobacco when burnt, as in smoking, are :—carbonate of ammonia, nicotianin, empyreumetic oil, soot, and some gasni.
Nicotine seems to be the formidable principle of tobacco when used in the solid form, or As an infusion ; and the enipyreutnatic oil, when it is smoked, or when obtained by destructive distillation. The action of nicotina is highly poisonous ; a quarter of a drop will kill a rabbit ; one drop can destroy a dog. It is distinguished from the other alkaloids obtained from the tribe of the Solanacece by not causing dilatation of the pupil ; the external application of it to the eye produces other very alarming narcotic symptoms. The tenth part of a grain put into the eye of a cat causes strong convulsions, with foaming at the mouth, quick respiration, accompanied with rattling in the throat and rapid palpitations of the heart, which can be heard at a considerable distance, staggering, and paralysis of the hinder extre.
mities, which symptoms disappear in an hour.
The empyreumatic oil, in the quantity even of a single drop placed on the tongue, excites convulsions and coma, without affecting the heart. It may prove fatal in two minutes.
Tobacco, therefore, is a very powerful agent, the active principles of which are extracted by water, either in the form of infusion or decoction. The local effects of Eoba•ncco-leaves, or any preparation of them, are those of an acrid substance ; hence when taken internally they cause vomiting and purging, pain of the stomach and intestines, followed by inflammation and ulceration. The external application occasions irritation of the part, and if kept long in contact with it, inflammation : snuffing the prepared powder induces sneezing and increased secretion of mucus; chewing or smoking it causes increased secretion of saliva, with diminished appetite in those unaccustomed to its use.
Besides these local effects it has a secondary action, which results from the absorption of the active principles. It is immaterial b3 what channel they are introduced into the circulation the same consequences follow, and affect on the one hand the intestinal canal, the lungs, and the heart ; and on the other, the nervous centres of the brain and spinal chord. The former show themselves by nausea, vomiting, purging, pain and inflammation of the stomach, and here and there of the intestines ; on the lungs, by the slower, painful, and irregular respiration ; and after death the tissue of the lungs is found to be thicker, more injected with blood, and accumulations or extravasatiou of it. .The action on the heart, or probably the nerves of the heart, manifests itself by irregular, generally slower pulsations, and by the heart losing its irritability sooner than after natural death ; but the chief secondary action is on the brain and spinal chord, and this succeeds the external as well as internal application of it, but most so after injection into the rectum. Giddiness, weight, and pain of the head ; deafness, a feeling like intoxication, staggering, trembling, general weariness of the muscles, with convulsive contractions of them, or cramps, general insensibility, sleepiness, and death are the consequences.