Scientific American 14, 20.12.1851
Lichens are a family of plants, belonging to the class cryptogamia, containing about 1,400 known species, under several genera. Their substance is powdery, crustaceous, membraneous, coriaceous, or even corneous. They are common everywhere, adhering to rocks, trunks or trees, and barren soil. On ascending mountains, they are flourishing beyond the limit of all other plants even to the verge of the perpetual snow. - Many of them, fixing upon the hardest rocks, by retaining moisture, facilitate their decomposition and promote the formation of soil. Several of the species are used for sustenance in times of scarcity, by the inhabitants of the northern regions.
Iceland moss is exceedingly abundant in the arctic regions, and often affords aliment to the inhabitants, either in the form of gruel or bread, which last is very nutritous. The taste is bitter, astringent, and extremely mucilaginous. It is frequently employed in pharmacy, in the composition of carious pectoral lozenges and syrups, and is celebrated as an article of diet, in combination with milk, in coughs and pulmonary affextions.
Orchil (roccella tinctoria) is also an important article, though less now than formerly, on account of the fugitiveness of the rich purple and rose-colored dyes which it yields. Some of its tints, however, are capable of being fixed, and it is, besides, employed for staining marble, forming blue veins and spots. Several other lichens afford dyes of various colors, as litmus.
Lichen, Liverwort, or Algæ, are the stunted herbage of the arctic circle, and of barren heaths. In Iceland and Lapland, it is eaten in broths and milk, and even made into bread, its bitterness being removed by washing in hot waters. It contains much mucilage or gluten, and has been extensively used in pulmonary complaints, and as a demulcent, relieving cough, and correcting all acrid secretions.
Lichen, or Archil is famous for its dye of purple blue, violet, &c. It is mostly brought from the Canary Isles, and is there ground in a mill, mixed with pearl-ash and urine, and sold in cakes.
The dye of archil is very evanescent, but very beautiful. It produces the most beautiful purples on woolen and silk goods, by first dyeing the goods a cochineal red and then blueing them down in a warm bath of archel solution. Crimson silk receives its first preparation of archil before it is put into the mordant of the nitro-muriatic of tin which is the prior preparation for a bath of ground cochnieal. Many beautiful light purple silk ribbons are indebted to this simple plant for their glowing colors; very few who wear them are aware of the substances employed to add grace to their fress and ornament to their persons.