Their utility in the arts, and especially in dyeing—including the collection of a series of the commercial dye lichens, i.e., those used by the manufacturers of London, &c., in the making of orchil, cudbear, litmus, and other lichen dyes. While investigating the dyeing properties of the lichens, I made experiments, with a view to test their colorific power, on as many species as I could obtain in sufficient quantity, to render it at all useful to operate on—that number, however, being very limited (between forty and fifty).
Dr. Lindley adds, many parties may be able to aid his investigations, by furnishing information on their economic uses, and on their special applications in dyeing and other arts—(particularly on their employment, as dye agents, by the natives of Britain and other countries)—with specimens of the lichens so used, and their common names—specimens of fabrics dyed therewith—notes of the processes employed for the elimination of the dyes, &c. Parties resident in, or travelling through our western Highlands and Islands, the northern Highlands, Ireland, Wales, Norway, Iceland, and similar countries, are most likely to be able to afford this description of information—many native lichens being still used by the peasantry of these countries to dye their homespun yarn, &c.
He proceeded to treat—1. The vast importance of this humble tribe of plants in the grand economy of nature, as the pioneers and founders of all vegetation. 2. Their importance to man and the lower animals, as furnishing various articles of food. 3. Their importance in medicine, and especially in its past history, at home and abroad. 4. Their importance in the useful and fine arts, and especially in the art of dyeing. 5. Their affinities and analogies to other cryptogamic families, and to the Phanerogamia. 6. Their value as an element of the picturesque in nature; and, 7. Their typical significance.
He then adverted more especially to the subject of his communication, under the ten following heads:—
I. The colors of the Thallus and apothecia of Lichens—their causes, and
the circumstances which modify and alter them.
II. History of the application of their coloring matters to the art of dyeing.
III. Chemical nature and general properties of these coloring matters.
IV. Tests and processes for estimating qualitatively, and quantitatively the
colorific powers of individual species—with their practical applications.
V. Processes of manufacture of the Lichen-dyes, on the large and small
scale in different countries—with the principles on which they are founded.
VI. Nomenclature of the dye-Lichens, and of the Lichen-dyes.
VII. Botanical and commercial sources of the same.
VIII. Special applications of the Lichen-dyes in the arts.
IX. Commercial value of the dye-Lichens, and their products.
X. Geographical distribution of the dye-Lichens—with the effect of climate;
situation, &c., on their colorific materials.
Of the four first sections of his paper, the following is a very short summary or synopsis:—
Under the first head, the author spoke of chlorophylle and various organic and inorganic substances, which enter into the formation of the colors of the thallus and apothecia of lichens, and of the modifications of these colors depending on various degrees of—1. Exposure to air and light. 2. Temperature. 3. Moisture, &c. 4. Atmospheric vicissitudes. 5. Season of the year. 6. Nature of the Gonidic reproduction (i.e., gemmation). 7. Nature of habitat. 8. Organic decomposition. 9. Coalescence of parts, monstrosities, &c.
Under the second section, he traced historically the manufacture of Lichen-dyes, and the native use of Lichens as dye agents, among different nations, from the times of Theophrastus, Dioscorides, and Pliny, down to the present day, sketching briefly the ancient end modern history of orchil, cudbear, and litmus, and specifying the native use of lichen-dyes in different, countries of Europe, Asia, and America. He alluded more particularly to their application to the dyeing of yarns, &c., by the Scotch Highlanders, under the name of "Crottles." "The process of the manufacture of the various crottles, generally consisted in macerating the powdered lichen for two or three weeks, in stale urine, exposing the mass freely to the air by repeated stirring, and adding lime, salt, alum, or argillaceous and other substances, either to heighten the color or impart consistence. To such an extent did this custom at one time prevail, that, in several of our northern counties each farm and cottage had its tank or barrel of putrefying urine, a homely but perfectly efficient mode of generating the necessary amount of ammonia. In the county of Aberdeen, in particular, every homestead had its reservoir of "Graith,"[53] and the "Lit-pig,"[54] 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 chemical re-agents, are colorless, but which, when the lichens are exposed to the combined influence of atmospheric air, water, and ammonia, yield colored substances. This series of colored products is usually comprehended more for convenience sake than on account of chemical identity, under the generic term orceine."