3§4

DYEING AND CALICO PRINTING.

Alkanet.

The tinctorial matter now rarely used,-known as alkanet, alkana, or canette',is the root of a plant belonging to the natural order of the Boraginacece, calledAnchusa tinctoria. It grows wild in Greece, Asia Minor, Italy,- and some por-tions of Southern Germany. The root has been used in pharmacy andperfumery, chiefly as a colouring matter. Its immediate tinctorial principlewas first isolated by M. Pelletier, who called it anchusine,- or anchusic acid.MM. Bolley and Wydler obtained it in a state of great purity, and called italkana red. They prepare it by first exhausting the previously dried andsliced root with water, which dissolves and eliminates soluble vegetable prin-ciples. The residue is then dried, and treated with alcohol ; the violet-coloured alcoholic solution is acidified with hydrochloric acid, and evaporatedto dryness. The residue is next treated with ether, which dissolves thecolouring matter ; the ethereal solution is mixed and well shaken up withwater, whereby the colour is obtained in an insoluble state, and is dried afterthe removal of the fluids by decantation. Dr. Lepage employs sulphide ofcarbon instead of alcohol, and, after having removed the excess of the former-named liquid by distillation, he treats the residue with a solution containing2 per cent of caustic soda, and precipitates with a slight excess of hydrochloricacid. The precipitate is separated by filtration, and, after having beenallowed twenty-four hours for settling, is well washed with water, and dried.The material thus obtained is a deep red, brittle, resinous mass, insoluble inwater, soluble in alcohol and ether, to both of which it imparts a beautifulreddish-violet colour. An alcoholic tindture of this root is used for colouringthe spirit of thermometers. The alcoholic solution is turned blue by alkalies,and yields with bichloride of tin a violet precipitate. The same solutionyields with subacetate of lead a greyish-blue, and with acetate of alumina, ata boiling heat, a violet-blue precipitate.

The pure ’alkana red is not at all affedted by boiling its alcoholic solution,but if the alcoholic tindlure of the root be evaporated to dryness, withouthaving previously been acidulated with hydrochloric acid, there is a residueleft partly soluble in water, and imparting to it a brown colour, while whatremains undissolved colours ether greenish. This greenish pigment is,according to Dr. Bolley, formed at the expense of the anchusine, which fixeswater and gives off carbonic acid. The precise composition of alkana red isnot known. Dr. Bolley states that its formula is C35H40O8, but this is notproved with certainty to be corredfc.

Anchusine appears to adt as a feeble acid. Its hot alcoholic solution dyescotton, previously mordanted with alumina, a violet, and when iron mordantsare applied a grey. To 1 litre of alcohol (sp. gr. o'84g) 62 grms. of the alkanared are used. The colours obtained are not fast, and are very readily affedtedeven by very weak alkalies and acids.

M. Hausmann, of Mulhouse, introduced the alkana red in calico-printing)but it has never been used to any large extent, and is now altogether obsoletefor that purpose. The root and the prepared red are largely used for colouringpomades and hair-oils, as a rouge for the complexion, and as a colouringmatter for lozenges.

Safflower.

This substance, also known as wild saffron, is the produce of the Carthamustinctorius , an annual plant, a native of Southern Asia, and cultivated in India,