Fig. 134. Lecanora tartarea Ach. (S. H., Photo.).
d. Other Orchil Lichens. Though species of Roccella rank first in importance as dye-plants, purple and blue colours are obtained, as indicated above, from other very different lichens. Lindsay[1304] extracted orchil from about twenty species. Those most in use in northern countries are on the whole less rich in colouring substances; they are: Umbilicaria pustulata, species of Gyrophora, Parmelia and Pertusaria, and above all Lecanora tartarea ([Fig. 134]). The last named, one of the hardiest and most abundant of rock- or soil-lichens, is chiefly used in Scotland and Sweden (hence the name “Swedish moss”) to furnish a red or crimson dye. In Scotland all dye-lichens are called “crottles,” but the term “cudbear” was given to Lecanora tartarea (either the lichen or the dye-product); it was acquired from a corrupt pronunciation of the Christian name of Dr Cuthbert Gordon, a chemist, who, according to Bohler[1305], obtained a patent for his process of producing the dye, or who first employed it on a great scale in Glasgow. Johnson[1306] remarks that the colour yielded by cudbear, if well prepared, is a fine, clear, but not very bright purple. It is, he alleges, not permanent. Like other orchil substances it is without effect on cotton or linen.
e. Preparation of Orchil. A general mode of treatment of dye-lichens recommended by Lauder Lindsay[1307] for home production of orchil, cudbear and litmus is as follows:
1. Careful washing, drying and cleansing to separate earthy and other impurities.
2. Pulverization into a coarse or fine pulp with water.
3. Repeated addition of ammoniacal liquor of a certain strength, obtainable from several sources (e.g. putrid urine, gas liquor, etc.).
4. Frequent stirring of the fermenting mass so as to ensure full exposure of every part thereof to the action of atmospheric oxygen.
5. Addition of alkalies in some cases (e.g. potash or soda), to heighten or modify colour; and of chalk, gypsum and other substances to impart consistence.
f. Brown and Yellow Dyes. The extracting of these colours from lichens is also a very old industry. Linnaeus found during his journey to Lappland[1308], undertaken when he was quite a young man, that the women in the northern countries made use of a brown lichen for dyeing which is evidently Parmelia omphalodes ([Fig. 135]). He describes it as a “rich Lichenoides of a brown stercoraceous colour,” and he has stated that it grew in such abundance in the Island of Aland, that every stone was covered, especially near the sea. In the Plantae tinctoriae[1309] there is a record of six other lichens used for dyeing: Lichen Roccella, L. tartareus, L. saxatilis, L. juniperinus, L. parietinus and L. candelarius. The value of Lichen omphalodes was also emphasized by Lightfoot; the women of Scotland evidently appreciated its dyeing properties as much as other northern peoples.