... L. tartarea, known as cudbear, are used in dyeing woollen yarn. The Rocella tinctoria and fusiformis furnish the orchil, or orchilla weed of commerce, which is sometimes sold as a moist pulp, but usually in the form of dry cakes, known under the name of litmus; it produces a fine purple color. Our imports, which have amounted ... — The Commercial Products of the Vegetable Kingdom • P. L. Simmonds
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