RHA MNOXANTHIN.

411

acids. Robinin is distinguished from quercitrin by its greater solubility inboiling water, and by the colour it yields with acetate of lead ; its formula is,according to Zwenger and Drouke, CfjjHjoOjg.

Rhamnoxanthin.—Buchner* gives this name to a substance extradled byhim from the bark of the Rhamnus cathartica, and by Phipson, from the barkand leaf buds of the Rhamnus frangula. It is a yellow crystalline substance,sparingly soluble in water, but dissolved by alcohol, ether, and alkalinesolutions, with a purplish colour. It is volatile, even at common tem-peratures, subliming readily as a yellow crystalline body. When cruderhamnoxanthin is mixed with pure quartz sand and placed in a flask, and themixture very gently but continuously heated, a body is sublimed which hasall the appearance of alizarin, and yields with alkalies cherry-red solutions.

Colouring Matter of Thuya occidentalis.—Kawalierf has extradled fromthe leaves of this well-known coniferous tree a yellow body, thuyin, which,on being boiled with dilute sulphuric acid, is split up into an amorphous sugarand thuyetin:—

C20H22O12 + 2H 2 0 = C6H12O6+ C i4 Hi 4 08Thuyin. Sugar. Thuyetin.

It is probable that the two last-named bodies are identical with quercitrin andquercetin, which they greatly resemble both in their properties and composition.

Fustet, Young Fustic, or Zante Fustic is the decorticated wood of ashrub belonging to the natural order of the Terebinthacete, and botanicallyknown as Rhus cotinus , a native of southern Europe, as well as of some ofthe West Indian Islands. Fustet is a hard, compadt, beautifully yellow wood,imported in bundles and small fagots. The American fustet is more valuedthan the Italian growth. The wood contains—(1) a crystalline yellowcolouring matter; (2) a red substance; (3) a brown astringent principle. Theyellow colouring matter was first isolated by M. Chevreul, who named itfustin. Dr. Bolley has more recently investigated this substance, which heconsiders as identical with quercetin, and prepares as follows:^—The aqueousdecoflion of the wood is evaporated to dryness; the residue treated withalcohol, the insoluble matter retains the red pigment; the alcoholic solutionis concentrated by evaporation and mixed with water, whereby the yellowprinciple is precipitated as a crystalline crust, which after washing with coldwater is re-dissolved in alcohol and re-precipitated with water, thus yieldingthe pure material. Although fustin thus prepared in many respedts resemblesquercetin it differs from the latter in some respedts, yielding, for instance, anorange, and not, like quercetin, a yellow precipitate with protochloride of tin ;the alkaline solutions of fustin are red. Dr. Bolley feels inclined to ascribethese differences to a small quantity of the red colouring compounds. Stillthe identity of quercetin and fustin is not at all proved, and requires furtherinvestigation. The fustet red has never been examined, and is probably dueto an alteration of the yellow principle. The decodlion of fustet exhibits thefollowing readtions :—Its colour is orange-yellow; alkalies turn it red;

♦“Journal de Pharmacie’’ [3], xxiv., 50; and DinglePs “ Polytcchn. Journal,” 1865,clxxxviii., p. 143.

t Kawalier, “ Comptes Rendus de l’Academie de Vienne, xxix., io.

t "Bulletin de la Societe Chimique de Paris,” ii., 47g. Schweitzerische, “PolytechnischeZeitschrift,” ix., 22 .