Lichen Islandicus. Iceland Moss is found on the mountains of Northern Europe. Nat. Ord. Lichenes. Linn. Syst. Cryptogamia. 100 parts contain 44 of Starch, 3 of a bitter principle (Cetrarin, or Cetraric Acid), and 36 of starchey skeleton, besides sugar, salts, and colouring matter. Iceland Moss contains one kind of starch, which is coloured blue on the addition of Iodine (lichen starch), and one which does not become blue with this agent (Inuline). It also yields three peculiar acids - Cetraric Acid, Lichestearic Acid, and Fumaric Acid; a neutral substance and a green colouring matter (Chloro-thalle).*
Med. Prop. and Action. Demulcent and tonic, in the form of decoction or jelly. The bitter principle which renders the taste very objectionable is best extracted by washing the lichen in a weak solution of potash (1 part in 300 of water) or in alcohol, or in plain distilled water. It is considered highly nutritive.
Offic. Prep. Pecoctum CetrariAe (Iceland Moss oz. j.; Distilled Water Oiss. Wash the Moss in cold water; boil with the distilled water for ten minutes; strain. The product to measure about a pint). Dose, fl. oz. iv., or ad libitum. By further boiling a jelly is obtained.
In Scrofulous and Scorbutic cases, when accompanied by much debility; and also in debility arising from Diarrhoea, Dysentery, and other exhausting diseases, Iceland Moss, in the form of decoction or jelly, is regarded as a valuable tonic, and as a highly nutritive aliment.
797. In Phthisis, Iceland Moss (ut supra) has been much lauded, not only as a nutritive aliment, but as an expectorant. In the latter character, it has been recommended by Scopoli, Hertz, Schneider, and Stoll. Sir A. Chrichton also speaks highly of it. Its good effects, he says, consist in improving the matter expectorated, in diminishing the frequency of the cough, and rendering it more easy, in calming the irritability of the patient, and in preventing or moderating hectic fever. Many doubt its expectorant properties; they have doubtless been exaggerated.
* Pereira, vol ii , pt. i., pp. 23, 24. Lond. Med. Journ., vol. x. p. 299.