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 P R E F AC E. I N the catalogues of the Materia Medica, the produdlons of the animal and mineral kingdoms bear a fmall proportion to thofe of the vegetable. Though it muft be acknowledged that for fome time paft the medicinal ufes of vegetable fimples have been lefs regarded by phyficians than they were formerly, which probably may be afcribed to the fucceffive difcoveries and improvements in chemiftry ; it would however be difficult to ffiew that this preference is fupported by any conclufive reafoning drawn from a comparative fuperiority of Chemicals over Galenicals, or that the more general ufe of the former has adually led to a more fuccefsful pradice. Although what may be called the herbaceous part of the Materia Medica, as now received in the Britiffi pharmacopoeias, comprifes but a very inconfiderable portion of the vegetable world ; yet limited as it now is, few medicinal praditioners have a diftind botanical knowledge of the individual plants of which it is compOfed, though generally well acquainted with their effeds and pharmaceutical ufes. But the praditioner, who is unable to diftinguiffi thofe plants which he prefcribes, is not only fubjeded to the impofitions of the ignorant and fraudulent, but muft feel a diflatisfadion which the inquifitive and philofophic mind will be anxious to remove, and to fuch it is prefumed Medical Botany, by colleding and fupplying the information neceflary on this fubjed, will be found an acceptable and ufeful work j the profefled defign of which is not only to enable the a