418

DYEING AND CALICO PRINTING.

of protochloride of tin. A solution of aloetate of ammonia yields upon woola deep moss-green colour, and upon cotton a mouse-grey colour, which resistswashing with soap: when bichloride of tin is added to this bath, wool is coloureddeep .bistre-brown; and with addition of acetate of alumina the same bathproduces upon wool a good moss-green, and upon cotton a good grey colour.When woollen fabrics are steeped in a solution of aloetate of ammonia, anddried in the air, a solid green is produced.

Chrysammic acid by itself dyes wool a deep rich brown and silk a purplish-brown ; chrysammate of soda dyes wool cinnamon-brown ; with aluminousmordants chrysammic acid yields a beautiful violet, which, however, does notresist soap well. Previously stannated cotton tissues are dyed grey by chry-sammic acid, while upon the same fabric without any mordant at all it yields anut-colour ; chrysammate of ammonia yields, with the addition of bichlorideof tin, a salmon upon cotton.

It does not appear that at present either aloes or chrysammic acid are used,and in this country their application has never been extensive.

Turmeric.

The substance known in commerce as turmeric root is the undergroundstem (tuber) of a plant belonging to the Scitamineae, and botanically knownas Curcuma tinctoria or longa. The shape of this article of commerce, whichgrows in a wild state in some parts of China and India, is sometimes cylin-drical, but more frequently ovoid; its epidermis is yellowish-grey, whilewithin the colour is a bright yellow; it emits a strong odour, and its taste ispeppery, aromatic, and bitter at the same time.

The plant producing this root is cultivated in Java and Bengal, the lattercountry producing the better quality.

According to the Japanese there exists a variety of turmeric, known by themas Yo-kin, yielding a root of about the thickness of a finger, and only aboutan inch in length, and distinguished, externally by transverse stripes of abrownish hue.

Turmeric contains, according to Vogel and Pelletier, ligneous matter, starch,and a yellow colouring substance ; while Dr. Schiitzenberger found therein aquantity of pedtic acid and pedtin. The colouring matter of turmeric is verysparingly soluble in water, but alcohol, ether, the fatty and essential oils,dissolve it readily. The alcoholic solution of turmeric is thrown down, by theaddition of tin crystals, as a red precipitate ; by acetate of lead, a chestnut-brown ; by mercury salts, reddish-yellow; salts of iron colour the tindturebrown ; alkalies turn it brown ; weak acids do not adi upon the pigment,which is turned red by concentrated acids. The colouring matter of turmerichas received the name of curcumin.

We shall first give a brief review of the researches made upon this sub-stance by Vogel, Pelletier, Schlumberger, and others, and then communicatethe results of certain researches just published, which in a great measure con-tradidt the results obtained by the chemists just named.

Curcumin may be prepared by first exhausting the pulverised turmeric withwater; the substance is next dried, and afterwards exhausted with sulphide ofcarbon, which only dissolves fatty and resinous matters, but leaves the pigmentuntouched. The residual matter is further treated either with boiling alcohol