Experiments on the dyeing properties of lichens / by W. Lauder Lindsay.

  • William Lauder Lindsay
Date:
[1854]
Catalogue details

Licence: Public Domain Mark

Credit: Experiments on the dyeing properties of lichens / by W. Lauder Lindsay. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    gating native lichens on the small scale ; hut it remains for the manufacturer to test the permanence and utility of colours which may merely look brilliant without having any fixity. II. This subject is worthy of being followed out by the manufacturer on the one hand, and the chemist on the other,— a. On account of scientific interest,—the field being comparatively new and open, and at the same time most promising of good results. b. Were it only with the view of further developing the economic resources of our own country. c. Because the speculation (i.e., the substitution of home for foreign dye-lichens), promises to be remunera- tive, as the roccellas have frequently reached the high price of £1000 per ton in the London market. III. The collection and transport of lichens for the pur- pose of examining their colorific powers is very easy, viz.:— a. By simple desiccation and packing. b. By drying and pulverizing. c. By precipitating the colorific principles from a lime solution or a decoction by acetic or muriatic acid. IV. The colour of the thallus and that obtained by the action of Stenhouse's or Helot's tests on solutions of the lichen-colorific-principles do not always correspond in tint; more frequently the reverse obtains ; hence it is impossible from the colour or other external character of the thallus of a lichen to predicate the nature of the reaction of its alco- holic solution with chloride of lime, or the tint it will yield on ammoniacal maceration. V. The lichens richest in colorific principles, capable of yielding valuable colouring matters, are crustaceous and foliaceous species of a pale or whitish colour—whose alcoholic or aqueous infusion is nearly devoid of colour—which grow on rocks or stones, and in mountainous countries, or on sea-coasts. VI. The lichens most devoid of the same principles are species having a showy foliaceous thallus—attaining a con- siderable size—whose alcoholic and aqueous solutions are generally of the same colour with the thallus—and which grow on trees and in woods. VII. The colours educible from lichens are liable to be ma- terially affected, both as to quantity and quality, according to—