4] which
stood by every fireside, was as familiar an article of furniture in
the cots of the peasantry, as the "cuttie-stool," or the "meal
girnel." So lately as 1841 (and I presume the practice continues to
the present day), Mr. Edmonston stated that, of four or five native
dyes, used by the Shetlanders to color cloth and yarns, two at least
were furnished by lichens, viz., a _brown dye_ from _Parmelia
saxatilis_, under the name of "Scrottyie," and a _red_ one from
_Lecanora tartarea_, under that of "Korkalett." It is very probable,
however, that steam and free trade have gradually dispelled this
good old custom, even in the remoter corners of our island;
machinery-made articles being now readily supplied, at a rate so
extraordinarily cheap, as to render it absolutely expensive (as to
time, if not also as to money) to prepare colors, even by a process
so simple and inexpensive as that just mentioned."

Under the third head, he examined, in a general way, the chemistry
of the colorific and coloring matters of the lichens and the results
to which it has led, avoiding as much as possible the technicalities
inseparable from such a subject, and giving a short _vise_ of the
researches of Heeren, Kane, Rochleder, and Heldt, Stenhouse,
Schunck, Laurent, and Gerhardt, and others. "Our untaught senses
should undoubtedly lead us to expect the lichens, whose thallus
exhibits the brightest tints, to yield the finest dyes, and these,
too, of a color similar to that of the thallus, but experience
teaches us that the beautiful reddish or purplish coloring-matters
are producible in the greatest abundance by the very species from
which we should least expect to derive any, viz., in those most
devoid of external color. This, though at first sight very
remarkable, is easily explicable, when we remember that, in most of
the so-called dye-lichens, colorific principles exist in a colorless
form, and only become converted into colored substances under a
peculiar combination of circumstances.

"Some lichens contain coloring matters, ready formed, and these
exhibit themselves in the tint of the thallus of the plants, _e.g._
chrysophanic [or parietinic] acid in _Parmelia parietina_, and
vulpinic acid in _Evernia vulpina_. In other species we find
principles, which, while in the plant, and unacted on by