On these occasions, the patients have been seized with violent vomiting and purging of blood, attended with severe pains in the bowels, and a sense of burning heat, referred to the chest and stomach; cold extremities, fluttering pulse, laborious breathing, syncope, and death. The above effects have been produced by an ounce and a half of nitre; although, as _Dr. Gordon Smith_ has observed, the same quantity of this salt has been inadvertently swallowed _without_ the production of such tremendous consequences. From the experiments of _Orfila_, it appears that if this salt be inserted into a wound, it occasions a fatal gangrene. Its action is undoubtedly the effect of its acrid nature, destroying the vitality of the textures with which it comes in contact. It is not absorbed. _Organic lesions discovered by dissection._ In those recorded cases of death from the ingestion of nitre, the stomach has been found red, scattered over with blackish spots, and its mucous membrane disorganized. _Chemical processes for the detection of Nitre._ The property which this salt possesses of deflagrating with combustible bodies, affords a ready indication of its presence. The process also, which we have described under the history of nitric acid, (p. 312) as the one suggested by _Dr. Wollaston_, and adopted by _Dr. Marcet_ in his examination of sea water, furnishes an elegant mode of ascertaining the presence of a nitric salt. Cl. IV. NARCOTIC POISONS. These constitute a class of vegetable poisons, less extensive, perhaps, but of far greater importance and interest, than the one we have already considered. It would not be easy to enumerate the various purposes to which the active imagination of man has applied the tribe of narcotic plants. Medicines, poisons, intoxication, and madness, lie concealed beneath their juices. They have, in their turn, arrested the pangs of disease, and inflicted death upon the unsuspecting object of hatred and revenge; they have animated the courage of the warrior, inspired the enthusiasm of the poet, soothed the sorrows of the wretched, and furnished the debauchee with a daily source of sensual gratification; effects which, although apparently incompatible with each other, may be commanded by the same substance, in a different dose. It would be foreign to the plan of this work to enter into a physiological inquiry into the _modus operandi_ of these extraordinary agents; and the author relinquishes the labour with less regret, as he has already, in another work,[415] very fully considered the several theories which have been advanced for its explanation. OPIUM, and its PREPARATIONS.