Active Ingredients. - Iceland moss is devoid of odor, but possessed of a bitter taste, and in substance is mucilaginous. It contains about eighty per cent, of farinaceous matter, which is resolvable into lichenine, or lichen-starch, and the starch-like body called inuline. The former is insoluble in alcohol, ether, and cold water, in which last it swells up, but is soluble in boiling water. Iodine turns it blue, whereas inuline remains unaffected.

The bitter principle resides in the cortical portion, and is called cetrario acid. When pure it possesses the form of acicular white crystals, which are intensely bitter, and almost insoluble in water, though when boiled in water the crystals communicate to it a bitter taste. It is sparingly soluble in alcohol and ether, and readily soluble in alkaline solutions, forming soluble compounds. The proportion of acid present is about three per cent.; there are found also a little gum, extractive, uncrystallizable sugar, and other ingredients of minor importance.

Physiological Action. - Iceland moss, when deprived of its bitterness by prolonged maceration in water, becomes a nutritious food, and is employed as such by the Icelanders.

Therapeutic Action. - Iceland moss, having no properties that can be strictly called medicinal, takes its place simply with the light and farinaceous foods that often become useful for invalids, the bitterness being first removed by steeping the plant in some alkaline solution.

It has been recommended for disorders of the stomach, such as dyspepsia and chronic dysentery; also in affections of the respiratory organs, as phthisis and chronic catarrh.

Preparations and Dose. - Decoctum Cetrariae,

Lichenes Iceland Moss Cetraria Islandica 51

- ij. (15.

- 60.)