GO

ELEMENTS OF MATERIA MEDICA.

Methods founded on the parts of organized beings employed.— It someworks the vegetable and animal substances employed in medicine areclassified accordingto the parts used; as barks, roots, seeds, secretions, &c.

R. A. Vogel, Historia Material Mcdicae. Ludg. Batav. & Lipsias, 1758.

C. Alston , M.D. Lectures on the Materia Medica, 2 vol. London, 1770.

•J. C Ebermaier, M.D. Taschenhuch der Pharmaeie. Leipzig, 1809.

N. J. B. G. Guibourt, Histoire ab regee des Drogues simples, 2de. ed. Paris, 1826.3me. hd. 1836.

B. Classification of inorganized substances. —I am unacquainted withany natural-historical arrangement of the inorganized substances of themateria medica; that is, of an arrangement founded on the externalforms and structure of these bodies. Most writers' who have followedthe natural system in their descriptions of vegetable and animal medi-cines, have adopted a chemical classification i'or the inorganized medi-cinal substances; a mode of proceeding which I shall follow in thiswork. As an example of a natural-historical classification of minerals, Imay refer to the following work:—

F. Mohs, Treatise on Mineralogy, translated by W. Haidinger, 3 vols. Edin-burgh , 1825.

It may perhaps be useful to present the student with a classification ofall the crystallized substances employed as medicines; as far, at least, astheir primary forms have been determined. And here I must explain,that the forms of crystals are primary or secondary. “ A primar/ formis that parent or derivative form from which all the secondary firms ofthe mineral species to which it belongs may be conceived to be derivedaccording to certain laws.” ( Brooke's Familiar Introduction to Crystallo-graphy, 1823.) The secondary forms consist of all those varieties be-longing to each species of mineral which differ from the primary form.

All the known primary forms may be arranged in six groups, or sys-tems, as follows :—■

Group 1st. Regu lar or Cubic System : ( Octahedral System : Tessular System. Mobs).—The primary forms belonging to this group, are the Cube (or Hexahedron), tin Tetra-hedron, the Regular Octahedron , the Rhombic Dodocahedron, and the Trapezohedton. Ofthese the Cube is usually regarded as the fundamental form or type. The folowingpharmacological agents belong to this group:—

Bismuth

Carbon

Copper

Gold

Iron

Mercury

Phosphorus

Sdver

Chloruret SodiumBromuret Potassium

Ioduret PotassiumMuriate AmmoniaArsenious AcidAlum

Galena (sulpburet ead).

Group 2nd. Right Square Prismatic System : ( Square Prismatic System : pyrami-dal System, Mohs ).—The primary forms included in this group are, the Right Prim witha square base) also called Right Square Prism, or simply Square Prism), and th; Octa-hedron with a square base. The first is considered to be the fundamental form Thefollowing medicinal substances belong to this group:—

Chloruret Mercury (Calo- Ferrocyanuret Potassium Copper Pyritesmel) Red Antimony (oxisul- Peroxide Tin .

Bicyanuret Mercury phuret).—( W. Phillips.)

Group 3rd. Bight Rectangular or Right Rhombic Prismatic System: (RightPrismatic System). —This group includes the following primary forms; the Rigit Rec-tangular Prism, the Octahedron with a rectangular base (Right Rectangular Ociaiedron),the Right Rhombic Prism, and the Octahedron with a rhombic base (Right Rhombi: Octa-