A manual of materia medica and therapeutics : including the preparations of the pharmacopœias of London, Edinburgh, and Dublin, with other approved medicines / by J. Forbes Royle.

  • Royle, J. Forbes (John Forbes), 1798-1858.
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: A manual of materia medica and therapeutics : including the preparations of the pharmacopœias of London, Edinburgh, and Dublin, with other approved medicines / by J. Forbes Royle. Source: Wellcome Collection.

    27/828 (page 15)
    Rectangular and also Rhombic Octohedrons. VI. Double Oblique Prismatic: 3 axes all intersecting each other obliquely ; Doubly Oblique Prism and also Octohedron. By these various processes are obtained the Pharmaceutical pre- parations which are known by the names of Solutions, Tinctures, Wines, Vinegars, Infusions, Decoctions, and Extracts; also Dis- tilled Waters ; Spirits and Essential Oils ; likewise some Precipitates and Salts, though the production of these depends chiefly upon Chemical Decompositions and Combinations. (For a full account of the different processes consult Kane's Elements of Pharmacy.) PHARMACEUTICAL CHEMISTRY. Substances which are throughout identical in nature, are subject only to the ordinary laws of Physics ; but when su])stances different in nature, and minutely subdivided, come into contact, or are placed at insensible distances from each other, they become subject to a series of changes consequent on Chemical Attraction or Affinity. The result of this attraction is to unite two or more bodies together into one which has properties usually very different from the bodies of which it is composed. One great object of Chemistry is to de- termine what bodies are compound, and what, from the inability of chemists to separate them into more simple bodies, should be considered as Elements. These are at present about 55 in number ; a majority of the most important of them form objects of study in Materia Medica, either in their simple form, or as constituents of compound bodies. As most bodies, when judged of by external characters, appear to be homogeneous, or composed of only one substance, the object of the Chemist is to ascertain whether this is actually the case, or only apparent. This he does either by the Action of Heat, or by present- ing to the compound body some other substance which has a greater affinity for one of its constituents, so that the other may be set free. This is called Analysis^ or the separation of a Compound Body into its constituent parts, the quantities of each being, if necessary, ascer- tained. As a Compound Body is capable of combining with other bodies, which may themselves be either simple or compound, it is clear that by the process of Chemical Analysis a complex body may be reduced either into the substances from the immediate union of which it has been formed, and which are called its Proximate Principles^ or into the elementary substances of which the latter consist, and which are then called its Ultimate Principles. When the constituent principles of a body can be so reunited as to reproduce the substance which has been analysed, the process is called Chemical Syn- thesis, and is the most certain proof of the correctness of an analysis. These Decompositions and Recompositions, or Combinations, form the chief occupation of the Chemist, are always going on in the