Volume 1

An experimental history of the materia medica, or of the natural and artificial substances made use of in medicine : containing a compendious view of their natural history ... / by William Lewis.

  • Aikin John, 1747-1822.
Date:
1791
Catalogue details

Licence: Public Domain Mark

Credit: An experimental history of the materia medica, or of the natural and artificial substances made use of in medicine : containing a compendious view of their natural history ... / by William Lewis. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    / wholly negledted, or regarded only as they affedt the medicine in point of elegance, I have exa- mined with no little care: and though it is not to be fuppofed, that the particular degree of each can be precifely determined; or its parti- cular fpecies, efpecially in regard to fmell, fully exprefled in words, any otherwife than by com- parifon with fubftances more known; or that any exadt limits can be always fixed, as between fetid and aromatic, grateful and ungrateful; I neverthelefs flatter myfelf, that the observations of this kind will furnifh, in many inftances, fufficient data to the phyfician forjudging what may be expedted from materials he has not ex- perienced. In this part, as in the defcriptive hiftory, great affiftance has been drawn from pharmaceutic chemiftry; for, in many vegeta- bles, the adtive matter is fo far divided and di- luted by the herbaceous inert fubftance; and in others, different kinds of adtive matter are fo blended together; that they cannot be difco- vered, or diftinguifhed, till they are extrafted, or feparated from one another, by the opera- tions of chemiftry. _ Some other experiments are, in particular cafes, very ufeful auxiliaries in this inquiry. Thus, a folution of vitriol of iron, made in water, is by many vegetables, turned to a black colour; by others, a folution of fulphur, made in alkaline liquors, is rendered milky’ or turbid, and of a ftrong. fetid fmell. It is not known, that any vegetable fubftance produces the firft of thefe effedts, but thofe which have an aftrin- gent power; or that any produces the lecond, but thofe partaking of an acid, which unites with and neutralizes the alkaline matter in the liquor, and difengages the fulphur which was thereby kept diflolved. By thefe criteria, lower degrees