The organic constituents of plants and vegetable substances and their chemical analysis / by G.C. Wittstein ; authorised translation from the German original, enlarged with numerous additions, by Baron Ferd. von Mueller.
- Date:
- 1878
Licence: Public Domain Mark
Credit: The organic constituents of plants and vegetable substances and their chemical analysis / by G.C. Wittstein ; authorised translation from the German original, enlarged with numerous additions, by Baron Ferd. von Mueller. 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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![oils but not by fixed oils. Tannic acid precipitates the aqueous solution. When evaporated with hydrochloric acid and chlorate of potash (or with chlorine-water), it leaves, a remnant which reddens the skin like alloxan and imparts to it a. peculiar smell; the solution of the said residue, when mixed with alkalies and salts of sub-oxyd of iron, acquires an indigo-blue coloui, and ammonia imparts to the residue a purple-red (murexid) coloui which does not turn violet by alkalies (distinction from uric acid). [J. Williams gives the following method for preparing Caffein. Mix finely-pulverised guarana with one-third hydrate of lime and moisten with water. After an hour or two exsiccate at a gentle heat, and exhaust with boiling benzol; filter and evaporate, but not to dryness. Treat with boiling water and digest on. the water-bath to the expulsion of all traces of benzol. Filtei through wet paper, and evaporate to a small bulk, from which the C. will separate after twenty-four hours pure and colourless.— According to H. M. Smith, Caffein is contained to the amount of OT33% in the leaves of Ilex Cassine L.—Thomson avers that in roasting coffee a great amount of Caffein is lost, which may be regained by adapting to the burner a tube of about three feet length wherein the vapours of C. are allowed to condense. One pound of coffee yields on an average 75 grains of Caffein. C. is insoluble in a concentrated solution of potassic carbonate. By treating an infusion with subacetate of lead, concentrating and adding car- bonate of potash, the C. is precipitated and may be obtained pure by dissolving in alcohol and evaporating. By passing the gas, evolved from chlorate of potash and hydrochloric acid, into an aqueous solution of Caffein and evaporating to dryness on the water-bath, a blood-red residue is obtained. One part Caffein in 1000 parts of water may thus be detected.] Cailceilrill. Bitter substance of the Cailcedra-bark (from Khaya Senegalensis). Extract with hot water, evaporate to a honey consistence, treat with alcohol of 33° Baume, add to the solution sub-acetate of lead which precipitates a red dyeing matter, filter, remove from the filtrate the alcohol by distillation, dissolve again in a little alcohol, remove the lead by sulphuret of hydrogen, evaporate, shake the aqueous liquid with chloroform and bring the latter solution to dryness. A yellowish, gum- resinous, brittle, very bitter substance, mollifies easily in hot water, dissolves readily in alcohol, also in ether, chloroform, little in water, of neutral reaction, yields a voluminous white precipi- tate with ether. Consists of 64-9 C, 7'6 H and 27'5 O. Calendulin. A substance, similar to vegetable mucilage, in the flowers and leaves of Calendula officinalis. It is obtained by treating the alcoholic extract, after it has been freed from a green, waxlike substance, with water; a voluminous, slimy](https://iiif.wellcomecollection.org/image/b21957927_0055.jp2/full/800%2C/0/default.jpg)
