WarasCHAPTER XVIII. Colouring Matters of Unknown Constitution.

The Natural Organic Colouring Matters
By
Arthur George Perkin, F.R.S., F.R.S.E., F.I.C., professor of colour chemistry and dyeing in the University of Leeds
and
Arthur Ernest Everest, D.Sc., Ph.D., F.I.C., of the Wilton Research Laboratories; Late head of the Department of Coal-tar Colour Chemistry; Technical College, Huddersfield
Longmans, Green and Co.
39 Paternoster Row, London
Fourth Avenue & 30th Street, New York
Bombay, Calcutta, and Madras
1918

Kaikki kuvat (kemialliset kaavat) puuttuvat // None of the illustrations (of chemical formulas) included.

Waras, also called "wars" and "wurrus," consists of a purplish resinous powder which covers the seed pods of Flemingia congesta (Roxb.), an erect woody shrub growing in the thickets and forests of the warmer part of India. According to Watt ("Dictionary of Economic Products of India," iii., 482), it is collected also in Africa in the neighbourhood of Harrar, and is sent to Arabia, chiefly to Yemen and Haddramant, where it is used as a dye, as a cosmetic, and as a specific against colds. According to Wardle, waras is distinctly inferior as a dye to kamala, which it closely resembles, and contains only a small amount of colouring matter compared with the yellow vegetable dyes of commerce. It is suitable as a dye for silk rather than for wool, but is quite useless with cotton. It has been introduced into England from Aden as an adulterant or substitute for kamala (Flückiger and Hanbury's Pharmacographica, 1879, 576). Under the microscope waras appears as orange-brown lumps, frequently circular and closely resembling kamala.

Flemingin, C₁₂H₁₂O₃ (provisional), is a dull orange-red crystalline powder consisting of star-shaped groups of minute prismatic needles, which melt at 171-172°, and closely resembles the rottlerin of kamala. Solutions of the alkali hydroxides dissolve it with an orangebrown tint, but these solutions when boiled do not deposit resinous matter, as is the case with rottlerin. On fusion with alkali salicylic acid and acetic acid are produced.

Silk suspended in a solution of flemingin in dilute sodium carbonate, and the whole gradually raised to the boiling temperature, is dyed golden yellow, slightly duller than the shade given by rottlerin; but, on the other hand, flemingin possesses much the stronger dyeing power of the two.

In addition to flemingin waras contains a trace of a yellow crystalline colouring matter, homoflemingin, melting-point 165-166° (C = 69,97; H = 5,75), together with some quantity of two resinous substances: (a) C₁₂H₁₂O₃ (?), melting-point 162-167°, and (b) C₁₃H₁₄O₃ (?), melting below 100°. Fused with alkali these latter gave salicylic and acetic acids, and appear to be allied to flemingin.

Added to a boiling solution of its own weight of sodium carbonate, waras dyes silk golden yellow shades, which are brightened by rinsing in very dilute acetic acid. Contrary to the statement of Wardle, it is to be regarded as a decidedly superior dyestuff to kamala (Perkin, Chem. Soc. Trans., 1898, 73, 659).