this branch of the materia medica by Chomel and Geoffroy, of France; by Vogel, of Germany; by Linnæus, and his pupil Bergius, of Sweden; and by Alston, Withering, Woodville, and others, of Great Britain, are generally known. All these writers have, treated of plants with a special reference to their medical uses, and the greater number of them have delivered formal systems. But beside what was effected by their inquiries, our knowledge of the subject has perhaps been still more increased by many of the other illustrious botanists mentioned in the preceding chapter. For while the latter have laboured to distinguish plants from one another, and to present them in a convenient method, few of them have failed to pay some attention to their medicinal virtues, and in many instances to make very interesting experiments of their effects on the human body.

The improvements in Mineralogy, during the period under review, huve also furnished many new articles, and extended our knowledge of others in the materia medica. The eminent services rendered to medicine in this way, by Scheele, Bergman, Klaproth, Vauquelin, and a large number of other distinguished mineralogists, are so generally known, that it is unnecessary to enlarge on the subject.

While the progress of natural history has contributed greatly to the enlargement and correction of the materia medica, the discoveries and improvements in in Chemistry have served still more eminently to promote the same end. When the employment of chemical remedies first became an object of much attention, in the hands of Paracelsus and his follow

ers, it was attended with so much errour, and embraced so many visionary and absurd opinions, as rather to corrupt and degrade medical science, than illustrate its principles, or guide their application. And, indeed, till the close of the seventeenth century, the doctrines of the chemist, when applied to medicine, served little other purpose than to amuse and mislead. But modern chemistry, in every respect a more just, rational, and dignified science than what had been called by that name in the preceding age, has opened resources for the materia medica of incalculable value; and is daily furnishing the enlightened physician with some of the most efficacious means of preserving health and combating disease.

The chemical inquiries of the eighteenth century have brought to light many new medicines, some of which hold the first rank for convenience, cheapness, and efficacy. From the same source physicians have learned to reject many inert and useless substances which formerly held a place in the materia medica. They have been taught, also, by chemistry, greater accuracy in forming their preparations, more easy, efficacious, and correct methods of exhibiting different substances, and more definite rules for adapting remedies to diseases. To enumerate those who have distinguished themselves by contributing to the improvement of the materia medica, through the medium of chemical investigations, would be to repeat the long catalogue of great chemists before given, whose names do so much honour to the last age.

Several systematic writers on the materia medica have been already mentioned. To these might be

added a much greater number, who have written learnedly and extensively on the subject, did not the limits of this review forbid such an enumeration. It would be improper, however, not to take some notice of what has been done in this department of medical philosophy by Lieutaud, Ferrein, and especially by Venel, of France; by Cartheuser, Spielmann, and Murray, of Germany; and by Hill, Lewis, Alston, Cullen, and Darwin, of Great Britain. these the work of Dr. Lewis, improved by Dr. Aikin, that of professor Cullen, and particularly the Apparatus Medicaminum of professor Murray of Goettingen*, are entitled to the largest share of esteem.

Of

The late work of professor Barton, on the materia medica of the United States †, forms a very valuable addition to the knowledge before possessed on this subject, and reflects high honour on its learned author. From the extent of information, the vigour of mind, and the ardent zeal by which this American naturalist and physician is distinguished, we may hope for further investigations, and richer discoveries of the medical treasures of our country.

* Professor Murray did not live to publish any thing on the mineral or animal articles of the materia medica. Professor Gmelin, of Goettingen, has published the Mineral Materia Medica, as a supplement to Murray's work; but he is not considered as having done justice to the subject.

+ Collections for an Essay towards a Materia Medica of the United States, 8vo, 1798. Under this modest title, Dr. Barton has presented a body of information, and discovered an accuracy and extent of learning, which might, without impropriety, have made higher claims. It is pleasing to observe that this work is so favourably received by the author's countrymen, that a second edition was lately demanded, into which he has introduced considerable additions and improvements.

Though it is impossible to enumerate all, or even the greater part of the new articles with which the materia medica has been enriched in modern times, it may not be improper to take some notice of a few of the most celebrated and useful.

The first application of Electricity to medical purposes belongs exclusively to the eighteenth century. It was before observed that Mr. Kratzenstein, of Germany, was the first person who applied the electric fluid to the cure of diseases, and that the course of experiment and inquiry on this subject was further pursued by the abbé Nollet, and by many others, at later periods. After correcting numerous errours arising from the extravagant calculations of the first experimenters on medical electricity, there remains no doubt of its efficacy in many diseases of nervous derangement and muscular debility, so that it is now fully established as an article of the materia medica.

Within a few years past, an agent, which is probably nearly allied to electricity, and which is denominated Galvanism, or the Galvanic Fluid, has become a popular application in certain diseases. The original discovery, together with the progress and gradual extension of this branch of philosophy, was mentioned in a former chapter. That this wonderful agent possesses great efficacy in many cases similar to those in which electricity is found to afford relief, seems to be too well attested to admit of doubt; but the extent of its application, the rules which ought to regulate it, and the degree and permanency of relief which it is capable of affording, have been so imperfectly investigated, that it is difficult to speak with precision or certainty on the subject.

The introduction of Factitious Airs into the materia medica may be considered as marking a splen did and very interesting period in its history. Some facts on this subject were stated in a preceding section, to which it will only be added, that though our knowledge of this important class of remedies is yet in its infancy, there are probably few sources from which more important aid to the physician may be expected to be hereafter derived.

The affusion of Water, cold and warm, on the body, in fevers and other diseases, deserves to be mentioned in this place as a new article in the materia medica, at least with respect to the principles and manner of its application. The simplicity, pleasantness, universal readiness of access, and unquestionable efficacy of this remedy, will, it is to be hoped, soon recommend it to general use. The honour due to Dr. Currie, of Liverpool, for his enlightened experiments, and valuable publication on this subject, was before noticed.

The efficacy and uses of Peruvian Bark have been better understood, within the last century, than in any former period. Its free and successful exhibition by modern physicians, in intermittent fevers, in scrofula, in cases of gangrene and mortification, and in numerous diseases of relaxation and debility, is well known. To the exertions of sir Hans Sloane and others, in introducing this medi cine into general use in Great Britain, much honour is due.

The use of Mercury has also been greatly extended, and its effects more accurately observed, during the century under review. The introduction of this metal as a remedy in a multitude of