Supplement to the Edinburgh new dispensatory / by Andrew Duncan.

Date:
1829
Catalogue details

Licence: Public Domain Mark

Credit: Supplement to the Edinburgh new dispensatory / by Andrew Duncan. 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.

    197/282 (page 187)
    1ST gelatine, but some other principle not yet sufficiently examined, which agrees with gelatine, in forming with tannin a precipitate comparatively insoluble in water. At the same time, it is but fair to remark, that my experiments were made with the infu- sion and tincture of cinchona, containing all the soluble principles of that substance, whereas Seguin’s observations are said to be derived from the examination of the iso- lated febrifuge principle, of which he gives the following characters: “ It precipitates the solution of tan, but not the solutions of gelatine and sulphate of iron.” On the contrary, my experiments teach me, that the entire infusion and tincture of cinchona precipitate the solution of tan, and also the solution of gelatine slightly, and the solu- tion of sulphate of iron copiously. But as the two last precipitates may be reasonably ascribed to the action of other principles contained in my infusion and tincture of cin- chona, I shall not insist upon them, but proceed to shew that, although cinchona actu- ally does precipitate the solution of tan, yet it does not contain gelatine. Exp. 1—{a.) An ounce of inf usion of galls was saturated, by adding to it, in diffe- rent portions, an ounce and a half of infusion of cinchona. The mixture was white and turbid, with a loose light precipitate. (&.) On filtration the fluid passed almost colourless, and perfectly transparent. (e.) The precipitate, when dried, weighed five grains. It had a yellow colour, and an opaque earthy appearance; was extremely friable, and did not adhere to the filtering paper. {d.) The filtered fluid gave no further precipitate with solution of cinchona; but with half an ounce of solution of gelatine, containing six grains of gelatine in each ounce, it produced a copious precipitate, and was saturated. Ce•) The precipitate, when separated by filtration, and dried also, weighed five grains, but was hand and brittle, adhered strongly to the paper, had a yellow colour, and exactly resembled a resin in appearance. Exp. II.—(a.) An ounce of the same infusion of galls was saturated by an ounce and a half of the same solution of gelatine. Immediately a very copious, whitish, tena- cious, and adhesive precipitate was formed. (b.) On filtration the fluid passed very slowly, and even after repeated filtration, still retained a slight degree of opaline bluishness. (c.) The precipitate, when dried, weighed fourteen grains and a half. It had a brownish yellow colour, was transparent, and had a resinous appearance and fracture. It was also hard and brittle, and adhered strongly to the filter. In every particular it resembled the precipitate produced in the former experiment {Exp. I. e.) by gelatine, after the infusion of galls was completely saturated by cinchona. id.) In the filtered liquor {Exp. II. b) infusion of cinchona produced no change. Exp. Ill—To an ounce and a half of the same infusion of cinchona, half an ounce of the solution of gelatine was added. It produced only a slight degree of turbidness, and changed the colour of the infusion from a pale greenish to a reddish yellow colour. When filtered, it passed perfectly transparent, and the bottom of the filter was covered with a red varnish ; but it had gained only one grain in weight. In other experiments with larger quantities, and stronger infusion of cinchona, the presence of tannin was more strongly indicated. Exp. IV.—Infusion of galls was not affected by rectified spirits of wine, in which isinglass had been long infused. Exp. V.—(a.) A tincture of cinchona was prepared by infusing it in the same rec- tified spirits. After it was filtered, some resin was separated by precipitation with water and filtration. (&.) With infusion of galls this tincture gave a copious precipitate, exactly resembling that produced by the same re-agent and infusion of cinchona. {Exp. I. c.) Exp. F/.—With tincture of galls the same tincture of cinchona gave no precipitate. Exp. VII.—In the mixed tincture {Exp. VI.) a copious precipitate was produced by diluting it with water. Exp. VIII.—A solution of carbonate of potash (salt of tartar) produced a copious white flaky precipitate in the solution of gelatine, which was soluble in boiling water, but was not precipitated from the solution by infusion of galls, until some acid was added. Exp. IX.—The solution of carbonate of potash changed the colour of the infusion of cinchona to a fine red, without disturbing its transparency. These facts seem to me sufficient to prove the difference between gelatine and the new principle in cinchona, which, for the sake of convenience, I shall venture for the present to denominate Cinchonin.