KamalaCHAPTER XVIII. Colouring Matters of Unknown Constitution. (Osa artikkelista)

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.

Kamala or Kamela is the orange-red powder which exists as a glandular pubescence on the exterior of the fruits of the Mallotus phillipinensis, Muell. (Rottlera tinctoria, Roxb.), a small evergreen tree, met with throughout tropical India, Burma, and Ceylon, also in Java, China, the Malay Islands, and Australia. The ripe capsules are gathered in February or March, and shaken in bags until the powder separates.

Kamala is employed by the Hindoos as an antithelmic drug and for dyeing silk and wool a bright orange colour. The fabric is dyed in a boiling bath containing 4 parts kamala, i part alum and 2 parts sodium carbonate (native barilla), previously wellrubbed together in the powdered state with a small quantity of oil of sesamum. The alum is sometimes omitted, but the addition of alkali is absolutely necessary in order to dissolve the colouring matter, which is of a resinous character and quite insoluble in water. Kamala is also apparently used for the adulteration of annatto, for according to Perkin (private communication), samples of calico obtained from India and presumably dyed with kamala have proved on examination to owe their colour partially if not entirely to annatto. Kamala was formerly employed in this country as a remedy for taenia, but appears now to be very little used for this purpose.

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According to Hummel and Perkin (J. Soc. Chem. Ind., 1895, 14), for silk dyeing it is best to add i part of kamala and 0,5-1 part sodium carbonate to boiling water, then to enter the silk and to dye at the boiling temperature for two to five minutes only. Other experiments indicated that the amount of sodium carbonate to employ should be regulated by the quantity of water used rather than by that of the kamala, namely, at the rate of 13-14 grams (Na₂CO₃, 10 aq) per litre. After dyeing fora short time with the addition of alkali only, to the extent of one-fifth of the weight of the kamala used, the addition of alum or stannous chloride to the dye-bath makes the colour fuller and more orange. A similar but by no means identical effect is obtained by making a slight addition of sulphuric acid.

As pointed out by Perkin (loc. cit.}, rottlerin is decomposed by boiling sodium carbonate solution, and the colour ultimately fixed on the fibre most probably consists of rottlerone. Although rottlerin itself does not dye mordanted fabrics, the potassium and sodium salts of this colouring matter give on calico mordanted with aluminium and iron pale orange-red and brownish-black shades.

Pure Java kamala contains, according to Flückiger (Arch. Pharm., 1892), 1,363 to 1,488 per cent, of ash, whereas in the kamala examined by Anderson (loc. cit.) 3,49 per cent, was present. The best commercial varieties usually contain about 5 per cent, of mineral matter (Seidler and Waage, Ber. Deut. pharm. Ges., 1891, 80); but the inferior qualities are highly adulterated (50-87 per cent.) with sand, earthy impurities, red brick-dust, etc. (Perkin, loc. cit., and J. Soc. Chem. Ind., 1900