400

DYEING AND CALICO PRINTING.

addition thereto of the quarter of its bulk of alcohol, is repeatedly shaken upwith ether, which dissolves phloroglucin and quercetic acid. The liquidshaving been allowed to settle, the upper layer (ether) is decanted off andevaporated to dryness, the residue is taken up with water, and the solutionprecipitated with basic acetate of lead. The filtrate yields, after treatmentwith sulphuretted hydrogen, to eliminate the lead, and removal of the sulphideof that metal, on concentration, crystals of phloroglucin, CgflgOj, a kind ofsaccharine matter related to orcin, and also discovered by Hlasiwetz amongthe produdls of decomposition of phloretin. The plumbic precipitate is firstwashed, next suspended in water, and decomposed by a current of sulphurettedhydrogen, and the resulting liquid, after filtering off the lead compound, isconcentrated either by evaporation in vacuo or by gentle heat in a current ofhydrogen gas. The crystalline matter obtained is purified by re-crystallisa-tion and decolouration over animal charcoal. The silky-looking needle-shapedcrystals thus obtained are quercetic acid,—a weak acid, hardly soluble incold water, soluble in boiling water, alcohol, and ether; the acid slightlyreddens blue ljtmus-paper, and has an astringent taste ; it reduces nitrate ofsilver, and imparts to perchloride of iron a blue colour, while the acidassumes in the presence of alkalies a magnificent purple-red. Sulphuric aciddissolves quercetic acid, yielding a red-brown solution, from which waterprecipitates a red flocculent matter, soluble in alkalies with a purple colour.The formula of quercetic acid is, according to Hlasiwetz, C i5 H io 0 7 .

Paradatiscetin precipitated from the potassic solution by hydrochloric acidis purified by being first washed with boiling water, next dissolved in strongalcohol, and precipitated by acetate of lead, whereby the unaltered quercetinis removed. The lead from the filtrate is removed by sulphuric acid, and theliquid, after filtration, concentrated by evaporation to one-third its bulk.This stage having been reached, the addition of water causes the precipitationof a bulky, white, flocculent mass, which, when re-dissolved in boiling hot butvery dilute alcohol, yields, on cooling, shiny yellowish needle-shaped crystals.This substance is an acid, yielding with bases—and especially baryta andstrontia—well-crystallised compounds. Paradatiscetin, the a.id named, isvery sparingly soluble in cold or boiling water, but readily soluble in weakalcohol; less soluble in ether. Its alcoholic solution is coloured an intensedeep purple by the addition of perchloride of iron ; acetate of lead does notprecipitate the alcoholic solution, but yields with the aqueous solution a yellowprecipitate ; weak caustic potassa and soda dissolve paradatiscetin, the liquidat first appearing yellow, but soon turning grass-green on contadt with air;addition of an aqueous solution of bromine colours the aqueous or alcoholicsolution first red, and next brilliant violet; addition of an alkali to this liquidturns the mixture blue; and if next hydrochloric acid be added, there ensuesa red flocculent precipitate, which yields with alcohol a red solution. Chlorinewater causes a brown-red colouration, while the solution of paradatiscetinis coloured reddish-brown by solution of bleaching-powder.

When submitted to heat, paradatiscetin fuses, yielding a reddish-yellowmass. The composition of this substance is—

Ci5Hio06= C^HjoC^ — O.

Quercetic acid.

The baryta salt, 2Ci 5 H I0 06,Ba,H 2 0 2 , crystallises in needle-shaped crystals.