The decennial revision of the United States Pharmacopoeia involves so many changes in remedies and formulae, that a treatise on Materia Medica must of necessity be newly edited to make it conform to the only official standard. I have, accordingly, revised my work, have changed the formulae as required by the new Pharmacopoeia, and have added to the list of remedies many that have only recently appeared. In so doing I was brought face to face with the important question of admitting proprietary medicaments. The Convention for the Revision of the Pharmacopoeia, at its last session in Washington, instructed the committee to whom the work of revision was intrusted to omit from the work all proprietary remedies or preparations. Those instructions were obeyed, and only those synthetical products not proprietary were given a place in the list of remedies. As a member of the Revision Committee I coincided in the propriety of this action, and I may seem inconsistent now that in my treatise I have admitted many of the remedies in question. But the functions and sphere of the two works differ. The Pharmacopoeia is an official guide for pharmacists and physicians, and must therefore pursue a conservative course in admitting new remedies, and refuse its countenance to those of proprietary origin, either secret or protected by letters patent. A treatise on Materia Medica should, as a rule, be governed by the same considerations; but in the case of the new synthetical products, so important are their attributes, so largely have they come into use, and so great is the demand for true information regarding them, that a text-book would be considered wanting in thoroughness and completeness if it contained no reference to the more important of them at least. I have therefore given an account, more or less complete, of various members of the group. It is the less necessary to include all that have been proposed and used to some extent in medical practice, since not all have proved useful, and many agree so closely in their actions that one may be substituted for another in the treatment of the morbid states to which they are adapted.

As the new Pharmacopoeia has employed the metric system in its weights and measures, it becomes necessary for all systematic works treating of the Materia Medica to follow its example. That my readers unacquainted with the metric system may have no difficulty, I have added in a brief appendix a tabular statement of the equivalents of weights and measures from one Troy ounce down, for which I am indebted to the Pharmacopoeia.

I venture the expression of my belief that this new edition will prove still more worthy of the remarkable favor which the work has enjoyed from its first appearance.

Roberts Bartholow, M. D. 1527 Locust Street, Philadelphia, October, 1893.