PART II.

MATERIA MEDICA,

1^ VERY substance employed in the cure of disease, whether-^ in its natural state, or after having undergone variouspreparations, belongs to the Materia Medica, in the extendedacceptation of the words. But in most Pharmacopoeias, themateria medica is confined to simples, and to those prepara-tions which are seldom prepared by the apothecary himself,but commonly purchased by him, as articles of commerce,from druggists and others.

Systematic authors on this branch of medical knowledgehave bestowed much pains in contriving scientific arrange-ments of these articles. Some have classed them accordingto their natural resemblances; others according to their ac-tive constituent principles; and others according to their realor supposed virtues. Each of these arrangements has its par-ticular advantages. The first will probably be preferred bythe natural historian, the second by the chemist, and the lastby the physiologist. But every scientific classification hither-to proposed is liable to numerous objections. Accordingly,in the Pharmacopoeias published by the colleges of physiciansof London, Dublin, and Edinburgh, the articles of the materiamedica are arranged in alphabetical order j and the same planis now almost universally adopted. I have therefore also fol-lowed it, subjoining to the name of each article, admitted byany of the British colleges, a short view of its natural., medi-cal, and pharmaceutical history ; and in thus forming a Dic-tionary of materia medica, I have generally adopted the no-menclature of the Edinburgh college.