DU. C. B. PLOWRIGHT ON BRITISH DYE PLANTS. 
389 
solution alkaline, causes the indigo to dissolve : wool now immersed 
and left in the mixture for an hour or two is dyed blue : that is to 
say, it becomes blue when taken out and exposed to the air. Not 
only does the mixture of Woad and water, maintained at the above- 
named temperature, produce a small quantity of indigo, but what 
is of practical use, it is capable of dissolving exotic indigo. This 
process is still in use in Leeds, where the really woaded blue 
cloths are dyed, that is to say, cloths dyed with indigo dissolved by 
the means of Woad. 
With various yellows, Woad gives shades of green. Specimens 
of greens produced by the subsequent application of Ash bark, 
Crab-apple bark, Weld, Dock, and Genista tinctoria will be found. 
With Cudbear from Lecanora tartarea a deep purple is formed. 
In bygone times Woad was used to form the basis of many 
colours. For instance, blacks, these were first dyed blue with 
Woad, and subsequently immersed in a vat of logwood, tannin, and 
iron. 
Reseda luteola. — This plant, with alum, produces the best and 
most permanent yellow of all our native plants. It has been used 
within the last quarter of a century for that purpose by dyers. The 
yellow is deepened by alkalies and rendered brown by iron. It is 
due to luteolin. 
Hypericum perforatum. — Fresh and dry with alum, and with 
or without subsequent treatment with ammonia, dyed wool greenish 
and brown. Four specimens are shown. 
Rhamnus frangula. — The bark with alum gives a nice orange 
brown. 
Rhamnus catiiarticus. — The fresh berries give, with alum, 
a dull green ; the bark a rich brown. 
Genista tinctoria. — Another dye plant, used in comparatively 
recent times, yielded various shades of yellow with alum ; per- 
manent, but lacking the beauty of those produced by Reseda. 
These yellows are darkened by alkalies. This plant was said to 
give better greens — hence its name “Dyer’s Green Weed” — than 
Weld. It contains luteolin, and genistin, CuHmOj, 
according to the researches of Mr. Perkin. It was formerly used 
for the production of the celebrated “ Kendal Green,” mentioned 
by Shakespeare. 
VOL. VII. 
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