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.

  • Wittstein, Georg Christian, 1810-1887.
Date:
1878
Catalogue details

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.

    30/358 (page 8)
    Alisniin. An acrid and bitter substance, occurring in the roots of Alisma Plantago, but only obtained in the extractive form, and has as yet not been closely examined. Alizarin = C20 He Oe + 4 HO. In the root of Rubia tinc- torum. Boil the pulverised root (madder) with water, precipitate the decoction with sulphuric acid, and boil the well-washed pre- cipitate with chloride of aluminium, in order to dissolve the dyeing substances. The solution, when mixed with a little hydrochloric acid, separates red flocks consisting of Alizarin, purpurin and resin. These flocks have to be dissolved in alcohol, or in diluted liquor of ammonia under addition of freshly precipitated alumina, which combines with the dyeing matters. This compound has to be boiled with concentrated solution of carbonate of soda, whereby purpurin is dissolved with deep-red colour, while Alizarin-alumina remains in the residue. The latter has to be freed from resinous matter by washing with warm ether, and is then decomposed by boiling with diluted hydrochloric acid. The remaining Alizarin has to be recrystallised in alcohol. It appears in long translucent, dark-yellow prisms of great lustre, of neutral reaction, and of bitter taste; loses the water at 100° to 120, turns opaque, darker red, fuses afterwards, and sublimates at 215° in orange-red needles; dissolves little in water, with purple colour in alkalies, with blood-red colour in concentrated sulphuric acid, and is precijii- table by water without change, with red-yellow colour in sulphide of carbon, and with gold colour in alcohol and in ether. [From the tubers of various Australian Droserae a substance has been obtained, which in physical properties closely resembles, and probably is identical with. Alizarin.—Baron von Mueller and Rummel.] Alkaloids. Compounds of carbon, hydrogen and nitrogen, with or without oxygen, mostly of alkaline reaction, and able to form salts with acids. Considering the short time (about fifty years), which has elapsed since their existence has been discovered, their number is rather considerable, and becomes greater con- tinually, though only the minor portion of the plants as yet treated for such have given positive resvdts, perhaps because either too little raw material has been employed, the quantity of alka- loids in vegetables being comparatively small, or because the proper method has not been adojated, or was not known, as is partly the case even at present. Investigations in this bi-anch of phyto-chemistry are nevertheless so far progressing, that I may venture some remarks regarding the approximate number and distribution of alkaloids. The classification of plants into natural gi'oups satisfies not only the botanist to a high degi-ee, but also the chemist, for, just as the former comprises all the plants that show a oertaiii harmony in