The sedative effects of tobacco are undoubtedly, I think, produced through the absorption of its active principle. The proof of this is that it operates in the same manner to whatever surface it is applied, whether that of the stomach, the rectum, the skin, or a fresh wound. Thus, two drachms of tobacco, applied to a wound, killed a dog in an hour. The slightly excitant effect, sometimes noticed in the increase of the pulse, and of the temperature, may be reasonably ascribed, as in the case of digitalis, to a sympathetic extension of the local irritation produced by it. That the primary general operation is upon the nervous centres, is to be inferred from the celebrated experiments of Sir B. Brodie upon dogs. An infusion of tobacco, thrown into the rectum, caused death in an hour by paralyzing the heart. But, if the animal were decapitated, and respiration sustained artificially, the poison produced no effect upon the circulation, though it must have equally entered the system. That death results from a cessation of the action of the heart, and not of respiration, as in the case of cerebral stimulants, is shown by the fact, noticed by Brodie, that, after apparent death, that organ was found perfectly quiescent. The empyreumatic oil seems to act differently; for, upon the same authority, the heart, after apparent death from that poison, was, on opening the body, observed to be beating with regularity and vigour. From what has been stated of tobacco and digitalis, the reader must have noticed a strong analogy between them; the most striking difference being, that tobacco has less effect in lowering the frequency of the pulse, and digitalis in producing nausea and vomiting.

3. Therapeutic Application

Tobacco is said to have been first introduced into Spain by Hernandez of Toledo, not very long after the discovery of America. it was sent to France by John Nicot, from Portugal, about the year 1560, whence originated the name of Nicotiana, conferred upon the genus. it was taken to England upon the return of the fleet under Sir Francis Drake from Virginia, in the year 1586.

The use of tobacco as an emetic, diuretic, errhine, and sialagogue, I shall treat of hereafter. in the present place we are to consider it as a sedative. it might possibly be employed, to a considerable extent, for the same purposes as digitalis; but its great liability to produce nausea and vomiting has very much limited its use as a sedative; and it is at present employed almost exclusively for the production of muscular relaxation, which this very nauseating tendency favours. it appears to possess some degree of anaesthetic power, for which it is occasionally though rarely used. The complaints in which it is most employed are those characterized by spasm, whether of the voluntary or the involuntary muscles. in consequence of its emetic action when taken into the stomach, it is almost never administered in that way for its sedative effects; being usually applied by enema, by inhalation, or externally.

Strangulated Hernia. Probably tobacco has more reputation in the cure of this affection than for any other purpose. it is certainly often very effectual, and has in many instances spared the necessity for the operation. it is used in the form of enema, and acts by inducing complete muscular relaxation, and possibly also by reducing the capillary circulation, and thus lessening the bulk of the strangulating structure. The plan recommended by the late Dr. Physick was to inject half a pint of the officinal infusion, containing a drachm to the pint, and, if this did not answer the purpose in half an hour, to repeat the dose.

Obstinate Colic - ileus. When colic has resisted the ordinary measures for producing relaxation, tobacco is often resorted to, and has in its favour the recommendation of the highest medical authorities. it is particularly in cases of ileus, or those attended with stercoraceous vomiting, that it has been recommended; but there is nothing in this particular phenomenon which specially calls for its use, except in so far as it indicates great violence or obstinacy in the affection. in obstinate constipation from an unknown cause, whether attended with spasm of the bowels or not, tobacco may be tried among other measures for obtaining relief. it has been recommended also particularly in colica pictonum; but it is not so much spasm, as a neuralgic and paralytic state of the bowels, that is to be overcome in this affection; and, as there are other remedies more efficacious for these purposes than tobacco, it is comparatively little employed. in all the above cases, the remedy is most conveniently used in the form of infusion, administered by the rectum. The smoke, thrown up the bowels, has been thought by some to be more efficacious, as it may make its way higher up the canal, and thus extend its influence more widely; but it is less by a direct influence on the bowels that the medicine acts, than through the general relaxation consequent on its absorption and operation on the nervous centres; and, in this respect, an equal effect may be obtained by the enema, which is besides much more convenient and manageable. Dr. Graves, of Dublin, and others before him, have found advantage, in colica pictonum, from the application of tobacco to the abdomen externally, by means of compresses of linen soaked in a strong decoction.

Spasm of the neck of the bladder, or of the urethra, with consequent retention of urine, may often be relieved by tobacco, employed either by injection into the rectum, or in the form of a warm cataplasm to the perineum. The same remedy has been recommended in dysury or strangury; and, in the form of cataplasm just referred to, may be tried with propriety; but, as an enema, laudanum is both more efficacious, and attended with less risk of unpleasant if not serious effects.

In spasm of the glottis, whether attendant upon inflammation in the adult, or in the form of croup in children, tobacco is sometimes of great service. in the latter affection, it was recommended by the late Dr. Godman, in the form of snuff rubbed with simple cerate, and applied to the surface of the throat and chest. The late Professor Chapman found the smoking of a cigar useful in the same disease. I have used the remedy in the shape of the leaves, soaked in hot water, and placed warm and soft about the throat as a cataplasm. in an instance of most violent and obstinate spasm of the glottis, in an adult female, immediate relaxation was produced in this way, after failure with depletory and other measures.