CHINESE YELLOW DYES.

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washed with boiling water as long as that fluid becomes coloured ; the materialis then strongly pressed, and dried. The dry residue is treated with boilingbenzol, which, on cooling, deposits crude curcumin. The author finds it abso-lutely necessary to use benzol, although it is a bad solvent for curcumin, 1 partrequiring 2000 parts of boiling benzol for solution ; but only by its use is itpossible to prevent the solution of a resinous matter present in the root. Thecrude curcumin so obtained is dried by pressure between folds of blotting-paper, and next dissolved in alcohol, whereby a small quantity of a yellowflocculent matter remains undissolved : the alcoholic solution is filtered, andnext precipitated by means of an alcoholic solution of acetate of lead ; the redprecipitate of plumbo-curcumin is first washed with alcohol, next decomposedby means of sulphuretted hydrogen, after having been suspended in water;the pigment, curcumin, remaining mixed with the sulphide of lead, is extractedby means of boiling alcohol, and this solution, having been left to evaporatespontaneously, leaves curcumin as a prismatic crystalline body, incapable ofsublimation. It fuses at 165°, and is decomposed when heated to a highertemperature. Curcumin is most soluble in alcohol and ether; concentratedmineral acids dissolve some curcumin, but do not leave it unchanged. Alkaliesdissolve it, the solutions exhibiting a bright red-brown colour; acids re-precipitate the curcumin. With compounds of lime and baryta, curcuminyields reddish-brown precipitates. The formula of curcumin is C i0 Hi 0 03, andthat of the lead compound C 2 oH I sPbO. When treated with nitric acid, cur-cumin yields oxalic acid. The curcumin obtained by the author exhibits, in ahigh degree the reactions above mentioned with alkalies and boracic acid.The author has obtained rosocyanin from his pure curcumin, but his researchesin this direction are not yet-complete : the substance hitherto known as cur-cumin, and above described, is, according to the author, a mixture of resinousmatters and curcumin.

Yellow Colouring Matters of Chinese Origin.

Dr. Rondot, in his work on the Chinese-green, enumerates the followingyellow dye-wares of vegetable origin as more particularly used in China :—

The Hohang-teng (yellow-weed) is a kind of reed or rush, of from o'oio toOC15 metre diameter; its taste is bitter; its shape cylindrical and knotty;externally the colour is reddish-brown, internally bright yellow. This substanceseems to be the produce of the Menispermum tinctorium or of the Cocculusfibraurea tinctoria ( tien-sien-tan of the Chinese and the cayvang-dang of theCochin Chinese). This substance yields its colouring matter to boiling water,and dyes tissues without any mordant. It is used to give a ground to fabricsintended to be dyed yellow with safflower.

The Hoang-pe-pi, the bark of the hoang-p6-mou, in all probability the barkof the Pterocarpus flavus or of a species of Hymcnolobium, is a tree growingto great height in some parts of China. This ware likewise yields its pigmentto water, and dyes cloth a reddish-yellow.

The Ti-hoang is the root of a plant, probably the Rhamncsia sinensis. Itscolour is similar to that of our common carrot internally.

Wongsky, Wongshy, Wongschy, Hoang-tchy, is the fruit of the Gardeniagrandiflora, a substance which has been investigated by Stein,* Von Orth,f

* “ Chem. Pharm. Centralblatt,” No. 9, p. 140.

4 “ Neues Repertorium iur Pharm., iv,, 12—17.