Active Ingredients. - To consider the whole subject of the active elements of tobacco, as used in its different forms, would be a task of much difficulty, - so many vexed questions have lately arisen. Until recently it was the custom to speak of tobacco as possessing two active ingredients, - nicotine, the alkaloid, which is present in the leaf, and an empyreumatic oil, which is generated only in combustion. The former was supposed (and the experiments of Brodie seemed to confirm this idea) to act chiefly as a paralyzer of the heart, while the oil exerted a general narcotic influence, without specially engaging the heart. According to these notions nicotine was the sole agent in the case of tobacco administered in watery solution (tobacco chewing, tobacco enemata), while tobacco smoke owed its power to the presence both of nicotine and of the empyreumatic oil. Snuff (as far as it is tobacco only) would owe its power to nicotine alone. More recent researches have rendered it at least very probable that tobacco smoke owes very little of its potency to nicotine, and very much to the combustion products, of which pyridine seems to be the most powerful. At any rate, it seems that to these substances the most formidable toxic effects may be ascribed.

To go into all these refinements is unnecessary. Pyridine and the other combustion-products of tobacco seem only to differ from nicotine in their action, so far as that they are milder, and less rapid in their toxic operation. It will be sufficient accordingly, for the purpose of this work, to regard nicotine as the active principle of tobacco. It is a powerful base, and completely neutralizes acids. It exists as a colorless, transparent, mobile fluid, possessing a well-marked tobacco odor (which is strongly developed when it is heated), and a sharp and burning taste long retained by the tongue. The specific gravity curiously (?) diminishes at successively higher temperatures; the vapor is exceedingly heavy; it turns the plane of polarization strongly to the left; it is very soluble in water (which it also absorbs freely from the atmosphere), in ether, in rectified spirit, in turpentine, and in fatty oils. Nicotine which has been kept some time is apt to turn a brownish-yellow color. (The whole question of the tobacco derivatives is in the utmost confusion, no two chemists agreeing in the matter.)

Physiological Action. - The most familiar of the physiological effects of tobacco are those which are experienced by young smokers, who rarely fail to poison themselves, to a greater or less extent, in their first trials. Nausea, giddiness, vomiting, or a feeling of deadly sickness, with cold sweatings, and exceedingly feeble pulse, are the ordinary results of first attempts to smoke tobacco which is even moderately strong. Of these effects it is difficult to say how much is due to nicotine, and how much to the empyreumatic products. It has even been stated by recent experimenters1 that nicotine is not present at all in tobacco smoke; and at any rate it is certain that the empyreumatic products are powerfully narcotic. In the few cases of fatal and nearly fatal results that have ensued from smoking,2 the symptoms have probably been due to the inhaling of the smoke into the lungs, whereby the empyreumatic products must have been largely deposited upon the extensive surface of the bronchial ramifications, and thus have been absorbed in considerable quantities. In the infusions and decoctions of tobacco leaves, which have been the ordinary mode of medicinal and criminal administrations of the drug, and the usual source of accidental poisoning, the active principle is undoubtedly nicotine.

The soluble parts of tobacco are easily absorbed, not only from the alimentary canal but also from the skin. The latter fact is proved by the case related by Dr. Blanchard.3 This author narrates the case of a man and his wife, who, to cure themselves of the itch, vigorously rubbed into the skin a decoction of tobacco. In a short time they were both affected; the man (who had scarcely wiped himself) more seriously than the woman. The latter was chiefly troubled with headache and vomiting, violent pains in the stomach, constant micturition, jaundice, muscular tremors, and painful cramps, besides constant vomiting and frequent stools, resembling those of cholera. Both patients recovered under the use of stimulants.

Fatal results have not unfrequently followed the administration of the decoction of tobacco in enema. Mr. Ede4 reports the case of a girl who in half an hour after the administration complained of faintness, and of feeling sick, and in another half-hour became quite collapsed, with cold sweats; she vomited, was slightly convulsed, and died in an hour and a half after the first reception of the poison into her system. On post-mortem examination the heart was found quite flaccid; neither stomach nor intestines presented any trace of inflammation. A case of gastric administration was that of a lunatic,5 who swallowed an ounce or an ounce and a half of crude tobacco, after keeping it some time in his mouth. He became suddenly insensible and motionless, with all the muscles relaxed, very feeble respiration and pulse, strong contraction of the pupils, and (later on) violent tetanic convulsions and profuse purging. After a temporary amendment, consequent on the use of the stomach-pump, the symptoms returned. There was profuse purging, with blood and mucus, and the patient uttered loud cries; the convulsions returned with brief intermissions, the limbs being at intervals rigidly flexed upon the body. There was also grinding of the teeth; death following in syncope, seven or eight hours after the taking of the tobacco. On post-mortem examination, forty hours after death, there was strong cadaveric rigidity, with congestion of the brain, the medulla oblongata, and the pons Varolii; the heart was empty, small, and contracted; the liver and kidneys were much congested; the gastric and intestinal mucous membranes were inflamed and partially abraded; the mesenteric veins were filled with dark blood; the bladder was contracted and empty; the blood was everywhere dark and fluid.