A dispensatory, or commentary on the pharmacopoeias of Great Britain (and the United States) comprising the natural history, description, chemistry, pharmacy, actions, uses, and doses of the articles of the materia medica / [Sir Robert Christison].

  • Robert Christison
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: A dispensatory, or commentary on the pharmacopoeias of Great Britain (and the United States) comprising the natural history, description, chemistry, pharmacy, actions, uses, and doses of the articles of the materia medica / [Sir Robert Christison]. Source: Wellcome Collection.

    25/1054 (page 17)
    _rnrropuctTion.—Metals and their Compounds. XV stituents are presented, is one of the best for administration. The chief ob- jection to infusions is, that they cannot be long kept, either in store by the druggist, or by the patient for consumption. ‘They may be pregerved, how- ever, for months, by pouring them while boiling hot into bottles, up to the top, and forcing in strong corks of good quality | Alsop]. Infusions have hitherto been made in this country almost entirely with boiling water, which is poured on the materials in a lightly covered vessel, and either allowed to cool before filtration, or kept for some hours at a low heat beside a fire or otherwise. But of late, the use of cold water in the way of percolation, or displacement, has been generally substituted in the higher departments of pharmaceutic chemistry ; and it may probably be em- ployed with equal advantage in the processes of ordinary pharmacy. Boiling water has the frequent disadvantage of dissolving, along with the active in- gredients of vegetables, starch and other principles, whose presence renders the infusions more apt to become acid or mouldy; and it favours certain re- actions between the proximate principles of plants, which have been adverted to in the remarks upon Decoctidns, and through means of which, active prin- ciples are either converted into insoluble compounds, or changed altogether in constitution. Percolation, or displacement with cold water, has the advantage of avoiding these inconveniences. Besides, it is observed that cold infusions generally have less tendency to decay than those made at a boiling temperature, above all when they are prepared in a highly concentrated form. Hence they have the additional advantage, that,—as vegetable infusions may often be pre- pared of very great strength in this way,—by preserving only that part which first passes through, the druggist may keep a store for current use, requiring dilution merely to answer the demand arising from the extempore prescrip- tions of practitioners. In this way, the exhausting of vegetable drugs by percolation with cold water might be turned to excellent account in the prac- tice of the retail-druggist and hospital-apothecary. Without such advantage, indeed, the process would, in various instances, be less convenient than the ordinary mode of making infusions; because’ the materials’ to be exhausted generally require to be in a fine state of division, and occasionally more time is necessary. The description of the process of Percolation will be found among the remarks on the preparation of ‘Tinctures; for most of which it has been introduced by the last Edinburgh Pharmacopeia, (and also in that of the United States,) where spirit is used as a solvent. The method of percolation without heat, has been hitherto adopted by the same College for only one preparation made with water as the solvent; namely, the infusion of Calumba, where it has the advantage of not dissolving starch. Butthere seems no reason why the same mode should not be applied to the preparation of the infusions of chamomile, cascarilla, catechu, chiretta, cusparia, gentian, krameria, pareira, quassia, red-rose, rhubarb, serpentaria, simaruba, sarsaparilla, and valerian; and possibly, even other officinal infu- sions might be added to this list. It,is probable that such preparations will keep better, if heated to 212° in well-corked bottles, by immersing them in boiling water; after which, any albumen which may be separated should be removed by filtration. METALS anp rHerm COMPOUNDS. On the extensive and most important list of officinal preparations comprised under these designations, it is unnecessary to make any general remarks. ‘The catalogue of preparations belonging to each metal has been gradually reduced in number, in the more recent editions of the Pharmacope@ias. But every one must regret that trivial or doubtful reasons of convenience, and imaginary dif- 2 it