Materia medica, pharmacy, pharmacology and therapeutics / by W. Hale White.

Date:
1907
Catalogue details

Licence: In copyright

Credit: Materia medica, pharmacy, pharmacology and therapeutics / by W. Hale White. 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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    PHARMACEUTICAL PROCESSES Lixiviation consists in the extraction with water of the soluble matter of the ashes of anything which has been ignited, the solution being called a lye. Maceration consists in leaving coarsely powdered solid organic substances in contact for some time, at the temperature of the atmosphere, with a liquid in a vessel which is frequently agitated. The resulting solution is poured off and added to the liquid obtained from the remaining substance by pressure. The whole may be concentrated by heat. Many extracts and tinctures are made by maceration. Percolation is a process for obtaining the soluble constituents of a drug by the descent of a solvent through it. The drug to be percolated is packed in a tall vertical cylinder, tied over at its lower end with muslin. The percolating fluid, or menstruum, is poured in at the top of the cylinder, and as it drops out through the muslin it is collected. The Marc is the material after its exhaustion by maceration or percolation. Many concentrated liquors, liquid extracts, and tinctures of vegetable drugs are pre- pared by percolation. Repercolation consists in using the liquid ob- tained by percolating a substance as the menstruum for percolating a second portion of the same substance, and using the liquid from this second percolation as a menstruum for percolating a third portion of the same substance, and so on as often as may be de- sired. The liquid extract of Belladonna is an example of repercolation. Scaling.—Scale preparations are made by drying concentrated solutions of drugs on glass plates. The solid left behind forms a thin film on the plate, and this film is broken up. Some preparations of iron are scale preparations. Standardizing.—The Pharmacopoeia directs that certain preparations made from vegetable drugs shall be standardized—that is to say, shall be made to contain a certain fixed proportion of the chief