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The abandonment of such notions may be considered as one among the many advantages which have arisen to medicine, from the cultivation of physiology.

Without farther introduction, I shall proceed to the main object of this work, and inquire how far a chemical agent may be capable of neutralizing, or of decomposing, a poisonous substance in the human body; and endeavour to ascertain the degree of confidence to which it may in each particular case be entitled; equally important is it to learn, whether certain vital agents may not be serviceable in cases of poisoning, either by promoting the elimination of the poison, or by producing a state of the system best calculated to resist its deleterious operation.

It may be safely asserted that we possess very few true antidotes; for although several of the mineral poisons may be neutralized or decomposed by various reagents, yet their destructive action is generally so rapid, that the mischief is effected before any chemical changes can avail; and, in other cases, the substances resulting from the chemical action, are as poisonous as the original ingredients, as in the case of the decomposition of Corrosive Sublimate, by the alkalies and earths, when the precipitated oxide is as virulent as the original salt; while, under certain circumstances, I suspect that the vital powers of the stomach are in direct opposition to those changes and decompositions which so readily, and so uniformly, take place in our laboratories. To vital agents then, the practitioner must principally look for succour; but before we can establish any general rules for the treatment of poisoning, it is essential to distinguish between the different modes in which poisonous substances produce their effects, or at least to determine the parts of the living system through which they act; for it will be found, that each poison has its own modus operandi, from which alone can be derived the particular indications of cure.