COLOURING MATTERS OF FLOWERS. 389

cochineal, but are more permanent, and resist.washing and exposure somewhatbetter.

Colouring Matters Contained in the Sorgho.

Sorgho-Red.—The plant known as “ durrha,” Sorghum, or Sorgho saccharl-ferum ,—a native of Northern China, and belonging to the family of the Gramineas,imported into Europe, and cultivated in some portions of Spain, France, andGermany, since the middle of the year 1853, chiefly for the purpose of theextraction of sugar,—contains several colouring matters, among which sorgho-red or sorgho-carmine, obtainable from the interior of the stems, after thesugar has been removed, by means of the action of dilute sulphuric acid.The pericarpium of the fruits or seeds contains, according to MM. Sicard,I. Itier, and Joulie,* two different red pigments, viz., sorghotin and sorghin,which are employed in China as dye-wares, yielding fast but not very brightcolours, somewhat like madder. M. Itier had in his possession pieces of thedyed linen and cotton fabrics which he had seen prepared while in China, andhe also had sorgho-red (from the stem of the plant), and sorghotin andsorghin, as sold in some parts of China; but the larger portion of the mate-rials brought by him and his co-travellers to Europe had been deposited withthe authorities at Paris, who (the revolution of 1848 intervening) seem to havelost sight of these matters. The cotton dyed with a mixture of sorghotinand sorghin, the cloth having been previously worked about in an emulsionof a peculiar nature, exhibit at first sight no difference from Turkey-red, but itis not so fast,—that is to say, does not stand acids, alkalies, &c., so well asgenuine Turkey-red.

Dr. Winter prepares from the stem of the sorgho a red colouring matter, byleaving the stems, deprived of the greatest portion of their juice, to ferment,piled up in heaps, until the colour has become red-brown ; the material is thendried, and next cut up to small fragments and treated with water, and after-wards with a weak caustic soda-lye. By this means the colouring matter isdissolved, and, on addition of dilute sulphuric acid, precipitated. The dyethus obtained is a flocculent matter, soluble in alcohol, in weak acids, and infeebly alkaline liquids. By the aid of tin salts, as mordants, this pigment canbe fixed upon woollen and silk fabrics, yielding a bright crimson-red colour,tolerably fixed and stable, withstanding light and washing with soap. The useof the sorgho stems as a dye material, after the elimination of the sugar anddestruction of the saccharine matter retained in the stems, is in China rathergeneral. There is nothing precisely known as to the nature and origin of thepigment thus applied as a dye. The bark of this kind of sorgho contains ayellow-coloured matter, xantholein.

Rose-Red, Pink, Red, and Blue Colouring Matters of Flowers.

Although the brilliant colours of flowers are not useful for applicationindustrially, a few words upon these pigments are not out of place.

MM. Fremy and Cloez infer from their researches that there exist threechief colouring principles in flowers, viz., cyanin, or a blue colouring matter;a rose-red or pink colouring material, in reality the same as cyanin, but

* During the reign of King Louis Philippe these gentlemen were, among some others, sentto China as an industrial and scientific mission, and from some of their reports (never pub-lished) portions of this article are made up.