(From mina, a mine of metalts). Minerals. The mineral kingdom furnishes numerous and very valuable remedies, first introduced by the chemical physicians, and, for a long time disregarded by the Boerhaavian school. They were supposed by the latter to be unalterable in the stomach by the digestive powers, and consequently incapable of producing any change in the circulating fluids, the source, in their opinion, of all diseases. Dr. Cullen first clearly pointed out, that many medicines, particularly opium and arsenic, produced considerable changes, though thrown up with an apparently undiminished bulk, and that therefore they acted on the stomach as a nervous organ, sympathetically connected with the rest of the system. Since that time, the opinions of the chemical sect have been revived with more distinct and more rational views, and copper, arsenic, barytes, with some other medicines of considerable power, introduced into the materia medica. In the views of the natural historian the study of mineralogy has been attended with greater difficulty.

In the system of Linnaeus, who was very imperfectly acquainted with minerals, the form alone was considered as the basis of the classification; and forms, at that time little known, or described with no very discriminated minuteness, led rather to confusion, than distinction. Cronstedt first conducted his arrangement with scientific accuracy, but his system was chemical, and the general rules, as well as the conduct of the historians of the other kingdoms of nature, rested their discriminations on external forms. Daubenton, the friend and coadjutor of Buffon, suggested an union of these two plans, but the revolution was completed by Werner and Hauy within a very few years.

It is unnecessary to mention a great variety of systematic arrangements. That of Cronstedt was comprised in four great divisions; earths, salts, inflammables, and metals, to which he lias added, in an appendix, compound and conglomerated stones, petrifactions, and volcanic productions. He has been followed, with no change in the great outlines, by Mr. Kirwan. While the chemical mineralogists were thus meliorating their system at their furnaces or their lamps, a considerable revolution was preparing in Germany and France. In the school of 1 reyberg, where the subject, from the neighbouring mines, forced itself on the attention of naturalists, Werner laboured at rendering the descriptive language more copious, more expressive, and more accurate. To every appearance of shade, colour, hardness, taste, smell, etc. he gave appropriate appellations, often with a disgusting harshness v\hich obscured what he attempted to explain, but with the most minute and accurate discrimination. Hauy, in France, was at the same time observing with minuteness the form of the crystals, and investigating by the most patient research, aided by the most accurate geometrical constructions, the original molecule, on which the future more compound crystal is moulded. In this enquiry he had an assistant in Rome de 1'isle, but his last most valuable work is wholly his own. That of Rome de lisle was published near twenty years since. Hauy, however, though he rests greatly on the form of the crystals, neither neglects the chemical analysis, nor the strict language of Werner; and the general merit of his work has lead us to prefer it as the most convenient book of reference, to ascertain the species intended, especially as his copious list of synonyms lead us equally to the best authors of the chemical and the Wernerian schools.

Hauy's first class contains the compounded acids, viz. those substances in which the acid is united to an earth, an alkali, and occasionally to both. The second comprises the pure earths, except where they may be united with an alkali. The third contains the combustibles, and the fourth the metals. The appendix is filled with those bodies whose nature is unknown, compound, and volcanic substances.

Werner, though he has so carefully improved the language of mineralogy, yet rests on chemical analysis as his chief support. The principal divisions of former authors it is impossible to overlook or neglect, for they are strongly pointed out by nature; and earths, salts, combustibles, and metals, are also his classes. He has added the classification of rocks, which he divides into primitive, transitive, alluvial, and volcanic. His object in this arrangement will be sufficiently obvious from the titles. Of Werner's system we have no very satisfactory account in cur own language. His work on the"external Character of Fossils" has been translated, but the language is disgusting and rugged. M. Brochant's two volumes of mineralogy, in French, give a much more favourable view of his doctrines; and this work is more valuable, as it goes hand in hand with that of Hauy, a circumstance which enhances the value of each. Mr. Jamieson's description of the minerals of Scotland, and a few others from, the school of Freyberg, are calculated rather to disgust than allure the student.

Werner has improved the science in one respect, viz. in preserving the natural families, which, like the natural orders in botany, connect kindred substances. Hauy has been equally successful in connecting these kindred tribes from the form of their crystals; and so just is his method, that the arrangement which these first suggested afterwards received their best support from chemical analysis. Another improvement of Werner is the arrangement of subjects, not from the predominance of their component parts, but from the character. Many reputed argillaceous earths have often the largest proportion of silex, but they are arranged with propriety as clays. This, though sometimes attended to, was not before the aera of the Freyberg professor strictly kept in view, and it has greatly improved his system as a natural one; the first and great object in every department of natural history.

The chief difficulty in mineralogy is the means of ascertaining species; and, when we proceed to other subjects which have been supposed less susceptible of the advantages of arrangement, we shall find the difficulty less considerable. Every author depends on the chemical nature of the object for the establishment of species; and Werner expressly observes, that bodies, which differ essentially in their chemical nature, differ also as species. The error lies in not affixing an accurate idea to the word"essentially" for Werner often-depends on differences purely accidental; and the establishment of sub species in almost every modern system shows the uncertainty of the foundation of specific differences. Hauy has formed his species on the chemical nature of substances, but he has added essential external characters, very striking and discriminated. Brochant has done the same, but not always with equal success.

It is a singular remark of prince Gallitzin in his

"Alphabetical Collection of Mineralogical Names," that the possible combinations of the nine principal earths, excluding the saline and metallic mixtures, exceed forty thousand, of which we have yet discovered scarcely more than fifty. How inexhaustible are Nature's stores, and what resources may not medicine and the arts have still in reserve ? The siliceous earths form nearly one half of the known combinations, the calcareous only furnish five, and the aluminous seven.

We have perhaps been led too far from our medical department; hut this subject has not sufficiently shared the attention of the English naturalists or physicians. We shall now return to our proper path, and endeavour to point out the comparative advantages of each class, in a medical view.

Earths. The first of these in the modern systems is the barytes, and we employ only the muriated salt, Though a solution of the pure or aerated barytes has been recommended vaguely, as an anthelmintic, and, ex ternally, as a destroyer of the life of a part. The purer or carbonated lime stones are absorbents, and, by this quality, they appear to act as astringents. From a loose analogy, they have been supposed useful in other excessive evacuations, where their power will not extend. The more incapable they are of absorbing acid, the less effectual they appear, unless when joined with some acids, they act according to common opinion as astringents in the intestinal canal. Their lithontriptic power has been sufficiently explained.

Magnesia is highly useful as an absorbent, and, when joined with acids, as a laxative: the clays we have found demulcent, and, from this effect, apparently astringent. The flints including the gems, though formerly celebrated, are now deservedly forgotten; nor, excepting the portion suspected by Dr. Gibbes in the Bath waters, is there any known form in which siliceous earth is swallowed, or in which it can be useful.

The strontia has been recommended as a diuretic, and an astringent, but we cannot ascertain the authority It is probably an absorbent.

The salts are more frequently advantageous, and, in their different forms, are useful laxatives, refrigerants, absorbents, and tonics. The two former objects are obtained by the neutrals; the two latter by the alkalis and acids. The volatile alkali is conspicuous as a stimulant, the vegetable acid as a refrigerant. Alum seems the chief objection to the general remark, though it appears to act occasionally as a laxative.

The Inflammables offer very few medicines, and with the exception of sulphur, and perhaps the petroleum, none of importance. The ambergris, and the asphal-tum, are now deservedly neglected. The succinum used only for its salt and oil.

The metals furnish the most numerous and the most valuable medicines, which we need not enumerate, as, with the exception of lead only, they are chiefly tonics; and, when we particularly examine its properties, we shall find them in some views according with those of the other metallic bodies. The metallic salts are often externally corrosive.

If then we find, in the inexhaustible variety of possible combinations, that we have yet discovered few, so in those which we have discovered, a very small proportion are useful as medicines; and when, from the whole of the mineral kingdom, with all the various preparations, we have selected twenty important ones, we need scarcely regret the loss of the rest. It must be recollected that the fifty known combinations from the forty thousand, are combinations of earths only; and that the combinations of the metals only with the acids would furnish as many more, of which a very small proportion has been actually discovered.

Kirwan's Mineralogy; Hauy Traite de Mineralogie; Mineralogie de Brochant; Wallerii Systema Minera-logicum.