About the thirteenth century an Italian, Tederigi by name, during
travels in the East observed the tinctorial powers of a certain class
of plant of low organization, called lichens, and introduced the
color into Europe under the name of archil. For this discovery he was
amply rewarded by the government, besides amassing a large fortune,
as the supply for years came from Florence. At first the weeds were
collected on the shores of various islands in the Mediterranean; but
on the discovery of the Canary Islands, in 1402, large quantities were
obtained from there. Later on they were imported from Cape Verde; and
now they are also obtained from Madagascar, Zanzibar, Angelo and Lima
and various localities in South America.
The weed does not contain any coloring matter already formed, but under
the influence of ammonia and the oxygen of the atmosphere gives rise
to archil. The manufacture of archil was for centuries carried on in
wooden troughs. Two hundred parts lichens were placed in the trough
together with about two hundred and forty parts of decomposed urine,
and the mixture well worked every three hours for forty-eight hours.
Five parts of slaked lime, one part of arsenious acid and one and
one-quarter parts of alum were then added, and the whole well stirred
and allowed to ferment. The stirring was repeated, from time to time,
for a month. The contents of the trough were then removed to casks, and
left to stand, thus improving the color. Archil is also one of the most
important dyestuffs used by the feather dyer, principally entering into
the composition of garnet, plum, brown, etc. Contact with acid will
destroy its coloring virtues by turning it a dull brown red.