Pharmacology, or the science of Materia Medica, treats of medicines in all their relations; Therapeutics, of remedies in general, and their application to the' cure and alleviation of disease.

Medicines are substances capable of producing, as an ordinary result, and by their own inherent power, changes in the healthy vital functions, which render them available for curative purposes. All these conditions are essential. Medicines are substances, or, in other words, are material. Influences not material, though efficient in the cure of disease, are not medicines. Substances necessary for the support of life, such as food, drink, atmospheric air, solar heat and light, are capable, if unduly applied, of deranging the vital functions: but this is not their ordinary operation; and they do not, therefore, belong to the category now under consideration. Again, bodies which have no inherent power of disturbing the functions may be rendered noxious, or remedial, by some extraneous agency. Thus, the dagger which destroys life in the hands of the assassin, and the knife which saves it in the hands of the surgeon, are incapable alike of injurious or beneficial action, when merely placed in contact with the body without any foreign impulse. Such bodies are evidently not entitled to the rank of medicines. There are, moreover, many substances which have the inherent power of even violently disturbing the system when brought into connection with it, which, however, have not been proved to possess remedial properties, and are never employed in the treatment of disease. These may be poisons, but they are not medicines. It is thus seen that all the conditions stated in the definition are essential. There are, indeed, a few substances, usually denominated medicines, which do not strictly fulfil these conditions. Such are anthelmintics, which are not used to modify the functions of the human system, but to act on certain foreign bodies which happen to be contained within it. Such, too, are the antacids given to neutralize acid in the stomach and bowels. But it happens that most of these substances really have medicinal properties, which render them useful for other purposes; and, so far as they are employed merely as anthelmintics or antacids, they may be regarded not as medicines, but as simply ranking in the more general category of remedies.

Remedies are agents, or influences of any kind whatever, capable of being usefully employed in the treatment of disease. Of course all medicines may be remedies; but there are very many remedies which are not medicines. To constitute any agent a remedy, it is not even m sary that it should be material. It may be a process or action whether mental or physical, a state or condition, a change of circumstance, even a negative quality, or the absence or diminution of some positive agency. Thus, we may class with remedies not only medicines, and the various substances, which, though not strictly medicinal, are yet employed therapeutically, as water, heat, electricity, etc., but also such influences as blood-letting, abstinence, exercise, rest, position, change of residence, cold, darkness, mental emotion, and many others that might be mentioned.

Pharmacology, which as before stated treats of medicines in all their relations, including of course their application to the cure of disease, has nothing to do with remedies not medicinal; whereas Therapeutics, which treats of all remedies in their remedial capacity, leaves out of view the properties of medicines not essentially belonging to them as such; their natural and commercial history, for example, their sensible and chemical properties, and their various modes of officinal preparation. There is an advantage, therefore, in combining the two sciences in one treatise; as each supplies the deficiencies of the other, and both combined convey all desirable information in relation to the origin, qualities, and uses of remedies.

In the present treatise, however, though some notice will be taken of those branches of the subject peculiar to Pharmacology, yet, as the United States Dispensatory, in the preparation of which the author participated, is especially devoted to that science, and treats in sufficient detail of almost everything exclusively belonging to it, he propose devote a more particular attention to therapeutics, which is but partially treated of in the Dispensatory, and in many important points has been quite overlooked. Indeed, the work which he now submits to the medical public, may be looked on as, in some measure, supplementary to the U. S. Dispensatory, affording by its arrangement a convenient plan for the perusal and study of that work, supplying its therapeutical deficiencies, and noticing those relations and properties of medicines having no immediate connection with therapeutics, only so far as may be essen -tial to the practical physician; reference being made to the Dispensatory for information of general or pharmaceutical interest, and for minute detail on all exclusively pharmacological points.

The work will consist of two parts. As there are many subjects, both in Therapeutics and Pharmacology, which are of a general nature, and cannot without inconvenience of arrangement, or the necessity for constant repetition, be considered in connection with special remedies, or even classes of remedies, it is proposed to treat of these preliminarily under the heading of General Therapeutics and Pharmacology, which will, therefore, constitute the first part of the work. The second part, much more extensive than the first, and forming, indeed, the main body of the treatise, will be devoted to the subordinate divisions and specialties of the two sciences, under the name of Special Therapeutics and Pharmacology.