Elements of materia medica and pharmacy / [John Murray].

  • John Samuel Murray
Date:
1808 [Fry and Kammerer, printers]
Catalogue details

Licence: Public Domain Mark

Credit: Elements of materia medica and pharmacy / [John Murray]. Source: Wellcome Collection.

    30/460 (page 24)
    a second, or even of a third or fourth, tnemiats, it] essens the. solvent power with regard to each. 'T here are some cases in which the solvent power is apparently unlimited, or in which no precise point of saturation can be pdinted out, such as the solution of sugar, gums, &c. in water. © The temperature or degree of heat has a very import- tant influence on solution, and in varying the point of sa- turation. In general every solution proceeds with more facility or rapidity at a high than at a low temperature, and the fluid is even capable at the high temperature of dissolving a larger portion of the solid, though with re- spect to different solids, this increase of solvent power, by a given temperature, is very different. ‘Solution, besides bemg one of the most important ope- rations in chemical analysis, is one of the most useful in pharmacy, the active principles of many substances being extracted, by means of their proper solvents. Saline sub- stances are dissolved in water, as are also gum, sugar, and other vegetable and animal products. Resins, camphor, essential oils, &c. are dissolved in ether, alkohol, or wine; and metals are rendered soluble and active by the different acids. The operation receives different appellations, ac- cording to the nature of the solvent, of the substances dissolved, and of the manner in. which it is performed. When we have a mixture of saline or earthy substances, of which part is soluble in water, or in any other fluid, while another part is insoluble, the one may be separated from the other by the due application of its proper solvent. The process thus performed is termed Lrx1v1aTIon, and the solution obtained, a Ley. When a fluid is poured on any vegetable or animal substance, so as to dissolve only part of its principles, the operation is termed Exrrac- Tron, and the part dissolved is said to be extracted. If it is performed without the assistance of heat it is termed Macereration; if witha moderatesheat, Digestion; if the fluid be poured boiling hot on the substance, and they are kept in a covered vessel till cold, it forms Inrusion. Lastly, Decocrion is the term given to the operation Mee ise the fluid is 4o%/ed upon the aastanicn to be dis~ solve