There still remains another point of view in which it is essential to regard the operation of a poison, in order to establish a distinction between those substances which, in a given dose, will destroy life under every circumstance of constitution, and those which occasion death in consequence of some constitutional peculiarity in the individual to whom they may have been administered, and which are innocuous to the general mass of mankind; the gradations by which food, medicine, and poison, are thus enabled to branch into each other cannot be defined, because the circumstances with which they are related, defy generalization. The distinction, however, must be acknowledged and preserved, and we know no terms better adapted for expressing it than those of _Absolute_ and _Relative_ poisons; and our readers are accordingly requested to receive them in conformity with this explanation, whenever they occur in the following pages. Every work professing to treat the subject of Poisons, abounds with instances, in which articles that, by universal consent, are considered innocuous, have occasioned the most direful effects. _Morgagni_ relates a case of a person who died from eating bread made with the farina of the chesnut. Dr. _Winterbottom_[151] says that he is subject to severe nettle-rash after eating sweet almonds. _Schenkius_ relates a case in which the general law of astringents and cathartics was always reversed. _Donatus_ tells us of a boy whose jaws swelled, whose face broke out in spots, and whose lips frothed, whenever he eat an egg: we might add many more examples, but it is needless to encumber a subject with illustrations which is already so obvious and indisputable. Nor do the anomalies of constitutional idiosyncrasies end here, for they not only convert food into poison, but they change poison into food, or at least, into a harmless repast. The most extraordinary exemplification of this on record is contained in the history of the old man at Constantinople, as related by M. _Pouqueville_, physician to the French army in Egypt, and who was a prisoner at Constantinople in the year 1798[152]. “This man,” says he, “was well known all over Constantinople, by the name of _Suleyman Yeyen_, or _Suleyman, the taker of corrosive sublimate_. At the epoch when I was there he was supposed to be nearly a hundred years old, having lived under the Sultans _Achmet_ III, _Abdul Hamet_, and _Selim_ III. He had in early life habituated himself to taking opium; but, notwithstanding that he constantly increased the dose, he ceased to feel from it the desired effect, and then tried sublimate, the effects of which he had heard highly spoken of; for thirty years this old man never ceased to take it daily, and the quantity he could now bear exceeded a drachm. It is said, at this epoch he came into the shop of a Jewish apothecary, and asked for a drachm of sublimate, which he swallowed immediately, having first mixed it in a glass of water.