The coloring of textile fabrics, such as cotton, wool, and silk, far
outranks in amount and importance that of leather, paper, etc., and
hence the former only will be considered here; but the theories and
facts relative to textile dyeing are applicable in a general way to
all other forms as well.
225. Plants as a Source of Dyes. Among the most beautiful examples
of man's handiwork are the baskets and blankets of the North American
Indians, woven with a skill which cannot be equaled by manufacturers,
and dyed in mellow colors with a few simple dyes extracted from local
plants. The magnificent rugs and tapestries of Persia and Turkey, and
the silks of India and Japan, give evidence that a knowledge of dyes
is widespread and ancient. Until recently, the vegetable world was
the source of practically all coloring matter, the pulverized root of
the madder plant yielding the reds, the leaves and stems of the indigo
plant the blues, the heartwood of the tropical logwood tree the blacks
and grays, and the fruit of certain palm and locust trees yielding the
soft browns. So great was the commercial demand for dyestuffs that
large areas of land were given over to the exclusive cultivation of
the more important dye plants. Vegetable dyes are now, however, rarely
used because about the year 1856 it was discovered that dyes could be
obtained from coal tar, the thick sticky liquid formed as a by-product
in the manufacture of coal gas. These artificial coal-tar, or aniline,
dyes have practically undisputed sway to-day, and the vast areas of
land formerly used for the cultivation of vegetable dyes are now free
for other purposes.
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