Thomson's Conspectus of the British pharmacopoeias.

  • Anthony Todd Thomson
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: Thomson's Conspectus of the British pharmacopoeias. Source: Wellcome Collection.

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    be perfectly free from impurities and empyreuma, and have the odour and taste of the volatile oils of the substances from which they are distilled. TINCTURES. Tinctures are spirituous solutions of vegetable, animal, and some saline substances. They are made either with pure alcohol, or with proof spirit. The first kind are precipitated by the addition of water, and therefore are more seldom em- ployed ; but the latter are very common additions to infusions and decoctions. They ought not to be united with any vehicle which can decompose the tincture, or separate anything from it in a palpable form. Tinctures should always be prepared by the apothecary, as the adulterations of them, which are daily practised by the druggist, are not easily detected. The ingredients should be reduced to a coarse powder, and the maceration made in close vessels, exposed to a heat of 80°, and frequently shaken. When completely made, they should not be put away upon the in- gredients, but filtered through bibulous paper, and kept for use in close bottles; for although they are not liable to spoil, yet, by the evaporation of the menstruum, their strength is altered, which, if they contain opium, or other active matters, may be productive of bad effects. Parmentier * proposes that one half of the spirituous menstruum be added to the vegetable ingredients at first, and after digesting six days, this part be poured off, and the remainder added. In six days more the whole is to be strongly expressed, and the two tinctures mixed - together. By this method he imagines more of the active principles of the vegetables are extracted, and the tinctures obtained of a more uniform strength. My method of making tinctures, is to mix the vegetable substance in powder with clean siliceous sand, and, having moistened it with the spirit, to put the mixture in an oblong funnel or percolator, and to pour the remainder of the spirit over it. By this method a strong tincture is procured in as many hours as days are re- quired by the present method of preparation. The Edinburgh College has adopted the percolator. Dr. Barton has proposed another method. He puts the ingredients into a bag large enough to hold twice the quantity, and then suspends the bag in the spirits. This acts gradually on the contents of the bag; the heavy tincture gravitates and fresh spirit is carried up until the whole is saturated.! iETHERS. iEthers are compounds produced from a new arrangement of the elements of alcohol, by the agency of the acids, at a heat * Annales de Chimie, vol. lxii. p. 40. t Med. Gazette, 30 Aug. 1844.
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