The cinchona barks : pharmacognostically considered / by Friedrich A. Flückiger ; translated from the original text, with some additional notes, by Frederick B. Power.

  • Flückiger, Friedrich A. (Friedrich August), 1828-1894.
Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: The cinchona barks : pharmacognostically considered / by Friedrich A. Flückiger ; translated from the original text, with some additional notes, by Frederick B. Power. Source: Wellcome Collection.

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    bark. These weights multiplied by 20 will give the percentage of ether-soluble alkaloids, and of quinine.” Another process, which is essentially that adopted by the Phar- macopceia Germanica (editio altera), but since improved by a slight modification, is as follows:— III. Twenty grams of the finely-powdered bark are repeatedly and actively agitated with a mixture of 10 grams of ammonia water (spec. grav. 0.960), 20 grams of alcohol (spec. grav. 0.830 to 0.834), anct l7° grams of ether (spec. grav. 0.724 to 0.728), and, after Standing for a day, 120 grams of the clear liquid are poured off. After the addition of 30 cubic centimeters of one- tenth normal hydrochloric acicl (containing 3.65 grams HCl in 1 liier) to the decanted liquid, the ether and alcohol are completely removed by distillation or evaporation, and, if necessary, so much hydrochloric acid added as is required to acidulate the solution. This is then filtered, and the cooled liquid mixed with 3.5 cubic centimeters of normal solution of potassium or sodium hydrate. After the alkaloids have been separated, the solution of alkali is added to the clear supernatant liquid until no further precipitate is produced. The entire precipitate is finally collected upon a filter, and gradually washed with a little water until the drops of liquid escaping front the filter, when allowed to fall upon the surface of a saturated neutral solution of quinine sulphate in cold water, no longer produce a turbidity. After being allowed to drain, the alkaloids are gently pressed between bibulous paper, then dried by exposure to the air sufficiently to admit of bringing thent into a glass capsule, in which they are placed over sulphuric acid, and finally completely dried in a water-bath. The weight of the dry alkaloids, which, according to the requirement of the Pharntacopceia Germanica, should amount to not less than 0.42 gram, or 3.5 per cent., does not relate to 20 grams of the powdered bark, but only to 12 grams of the same, since only 120 cubic centimeters of liquid were decanted. The alkaloids, which by this method are obtained somewhat less pure than by the preceding, may again be dissolved in hydro- chloric acid, precipitated by alkali, then taken up by Chloroform or ether, and, after the evaporation of the latter, weighed.1 The method of De Vrij, as adopted by the United States Pharmacopceia (Sixth Decennial Revision, 1880), for the assay ot Cinchona barks, is as follows :— 1 Compare Prollius, Archiv, der Pharm., 219 (1881), p. 86; Biel, Ibid, 220 (1882), p. 355; and H. Meyer, Ibid, 220, (1882), pp. 721, 812. The weight of the residue remain- tng upon the evaporation of the ether corresponds approximately to the amount of quinine.