404

DYEING AND CALICO PRINTING.

colouring glucosides in these berries appears proved by the labours of Persoz,*Gellaty,f Ortlieb,.J Schiitzenberger and Berteche.j|

M. Persoz observes, that when deco&ions of the berries are left for a lengthof time to themselves they enter into alcoholic fermentation, thereby depositinga crystalline matter, sparingly soluble in water. This appears due to a slowsaponification of one of the glucosides. M. Ortlieb found that when a decoc-tion of the berries is acidulated with sulphuric acid, and then boiled, the samereaction is effe&ed in a few minutes. M. Gellaty has extradled from theberries, by means of alcohol, a large quantity of a yellow, crystalline, insipidmatter, soluble in cold water and alcohol, but not in ether, and capable ofbeing split up, by means of ebullition with dilute sulphuric acid, into glucoseand another yellow flocculent body. The first-mentioned body he callsxanthorhamnin, and the derivative rhamnetin, and represents this readtion bythe following formulas:—

C 23 H 28 0 I4 + 3 H 2 0 = C I2 H 2 40 i 2 + CiiH io 05 .

Xanthorhamnin. Glucose. Rhamnetin.

The substance obtained by M. Ortlieb while boiling a deco&ion of the berrieswith dilute sulphuric acid, and that investigated by Dr. Schiitzenberger andM. Berteche, are evidently also rhamnetin, which latter, when properly puri-fied by means of dilute alcohol and ether, is a crystalline golden-yellow body,sparingly soluble, even in boiling water (i litre of boiling water dissolves653 milligrammes). What is dissolved is precipitated on cooling. The sub-stance is easily soluble in alcohol and ether. The last-named chemist foundthat the results of the elementary analysis of this substance agreed with theformula Ci 2 H io 05.

When rhamnetin is heated along with caustic potassa it is, like quercetinunder the same conditions, split up into a saccharine matter and an acid, thecomposition of which was not determined. If heated to 140°, in sealed tubes,with anhydrous acetic acid, rhamnetin is converted into several acetic deriva-tives, insoluble in water, of a pale yellow colour, and among which one isfound capable of separating from an alcoholic solution in white crystals.Rhamnetin may therefore be viewed as a polyatomic alcohol; and it wouldappear probable that, if the formula of quercetin is taken at C11H8O5, it is alower homologue of rhamnetin, but even if the identity of the two bodiesjust named were positively settled, which is not the case, there is no possi-bility of confusing quercitrin and xanthorhamnin, the latter being far moresoluble in water than the former.

Judging by its properties and composition, the substance extra&ed byDr. Kane from yellow berries, by means of ether, and named by him chryso-rhamnin, appears to be rhamnetin, and the same remark applies to the bodywhich M. Fleury named rhamnin, and which he obtained from the young twigsof the Rhamnus shrub.§ The rhamnoxanthin, which Buchner^T obtained fromthe bark and berries of a shrub related to the Rhamnus species, appears todiffer from rhamnetin by being volatile.

* “ Traite de l’Impression des Tissus,” vol. i.

+ “ Edinb. New Phil. Journal,” vol. vii., p. 252.

$ “ Bulletins de la Societe Industrielle de Mulhouse,” vol. xxx., p. 16.

I! Ibid., vol. xxxv., p.455.

§ “ Journ. de Pharm,,” vol. xxvii., p. 666.

11 Ibid., 3rd series, vol. xxiv., p. 50.