Cetraria. U. S. 1890. Iceland Moss. Iceland Lichen.—Under this name the U. S. P. formerly recognized the dried plant of Cetraria islandica Acharius, Lichen islandicus L. This plant, although known as a moss, is not a moss, but a lichen which grows in most northern latitudes and on elevated mountains further south, including the Northern United States.

The dried plant is of diversified color, grayish-white, brown, and red, in different parts, with less of the green tint than in the recent state. It was officially characterized as follows: " From 5 to 10 Cm. long, foliaceous, irregularly branched into fringed and channelled lobes, brownish above, whitish beneath, and marked with small, depressed spots; brittle and inodorous; when softened in water, cartilaginous, and having a slight odor; its taste is mucilaginous and bitter." U. S., 1890. Macerated in water, it absorbs rather more than its own weight of the fluid, and, if the water be warm, renders it bitter. Boiling water extracts all its soluble principles. The decoction thickens upon cooling, and acquires a gelatinous consistence without viscidity. After some time the dissolved matter separates, and when dried forms semi-transparent masses, insoluble in cold water, alcohol, or ether, but soluble in boiling water, and in solution forming a blue compound with iodine. Lichenin, or lichen starch, C12H20O10, resembles starch in its general characters, but differs from it in some respects. Lichenin has been found to consist of two distinct proximate principles, for one of which the name lichenin may be retained, while for the other no particular designation has been chosen, but which we may call lichenoid. According to Th. Berg (These de Dorpat, 1872), cetraria yields 35.15 per cent. of the mixed principles, of which 20 per cent. is of lichenin, and 15.15 of the so-called lichenoid. To separate them, a decoction of the moss, concentrated to a small bulk, and still hot, is treated by alcohol. The lichenoid is deposited in flocculi, which gradually unite in a viscid mass. This, being washed by alcohol until it ceases to be bitter, and then dried, yields a light friable matter partly soluble in cold water, with which it forms a yellow, limpid solution. To deprive it of mineral and coloring substances, it is dissolved in a little water, and precipitated afresh by alcohol. Lichenin is insoluble in cold water, but swells up and easily dissolves in hot water. It is insoluble in alcohol and in ether. It is only tinged by iodine. Lichenoid is, on the contrary, colored blue by that reagent. It is, in part, dissolved in cold water, and the undissolved part is equally colored blue by iodine. It is, like lichenin, insoluble in alcohol and ether. Both substances have strong analogies with starch, yet are distinct. For a further account, see J. P. C., 1873.

The name cetrarin has been conferred on the bitter principle. Herberger's process for extracting it may be found in the 18th ed., U. S. D. By it one pound of moss yielded to Herberger 133 grains of cetrarin, Schnedermann and Knop have ascertained that cetrarin consists of three distinct substances: (1) cetraric acid, C18H16O8, which is the true bitter principle, crystallizable, and intensely bitter; (2) a substance resembling the fatty acids, called lichen-stearic acid, C14H34O3, the crystals of which melt at 120° C. (248° F.); and, (3) a green coloring substance, which they name thallochlor. These principles are obtained perfectly pure with great difficulty. (Ann. Ch. Ph., lv, 144.) Hilger and Buchner (Ber. d. Chem. Ges., 1890, p. 461) give to lichen-stearic acid the formula C43H76O13, and to cetraric acid the composition C30H30O12, and both are shown to be dibasic acids.

The gum and starch contained in the moss render it sufficiently nutritive to serve as a food for the Lapps and Icelanders, who employ it powdered and made into bread, or boiled with milk, after having partially freed it from the bitter principle by repeated maceration in water. As suggested by Berzelius, the bitterness may be entirely extracted by macerating the powdered moss, for twenty-four hours, in twenty-four times its weight of a solution formed with 1 part of an alkaline carbonate and 375 parts of water, then decanting the liquid, and repeating the process with an equal quantity of the solution. The powder, being now dried, is perfectly sweet, and has been used to some extent in pharmacy as a substitute for acacia, although lacking in adhesiveness. (See also Gelatina Lichenis Islandici Saccharata Sicca (Germ. Unoff. Formulary), Proc. A. Ph. A., 1892, 455.) This plan which has been proposed of first extracting the bitterness by maceration in water or a very weak solution of an alkaline carbonate, and afterwards preparing the decoction, has been criticised, as the peculiar virtues which distinguish the medicine from the ordinary demulcents are thus entirely lost. A pint (473 mils) of the decoction may be taken during the day.

Iceland Moss has been much used in chronic catarrhs, especially of the pulmonary mucous membrane and even in phthisis. It acts chiefly as a mucilaginous drink, but as Kobert has found that cetrarin, is a stimulant to the gastro-intestinal mucous membrane and to peristalsis, cetraria probably is feebly tonic. A 20 per cent. tincture has been recommended in doses of twenty to thirty minims (1.2-2 mils) by Deymg and Brice-Moret as an anti-emetic (P. J., Oct. 30, 1897), which is confirmed by Gigon. (R. T., 1905, p. 610.)

Cetrarin, or Cetraric acid, C30H30O12; a white, crystalline, bitter principle, soluble in solutions of alkalies and their carbonates, in hot water and slowly in cold water. It is administered in the treatment of anemia, chlorosis and digestive disturbances. Dose, one and a half to three grains (0.096-0.2 Gm.).

Decoctum Cetrariae. U. S. 1890. Decoction of Cetraria. Decoction of Iceland Moss.

"Cetraria, fifty grammes [or 1 ounce av., 334 grains]; Water, a sufficient quantity, to make one thousand cubic centimeters [or 33 fluidounces, 6 ½ fluidrachms]. Cover the Cetraria, in a suitable vessel, with four hundred cubic centimeters [or 13 fluidounces, 252 minims] of cold water, express after half an hour, and throw the liquid away. Then boil the Cetraria with one thousand cubic centimeters [or 33 fluidounces, 6 ½ fluidrachms] of water for half an hour, strain, and add enough cold water, through the strainer, to make the product, when cold, measure one thousand cubic centimeters [or 33 fluidounces, 6 ½ fluidrachms]." U. S., 1890.

Saccharum Cetrariae.—Cetraria 1, sugar 1, water 100. Wash the cetraria with water to remove bitterness, then boil with 100 mils of water, strain and express lightly, and in the strained liquid dissolve the sugar and evaporate upon a water bath. When sufficiently firm remove from the bath and dry in an oven to a scale or a powder.

The Cetraria juniperina (probably Cetraria vulpina) of Europe is said to be sometimes used as a poison for wolves and foxes, while the wolfs moss (Ulfmossa) of the north of Europe contains vulpinic acid, C19H15O5, which has been found by Kobert to be an active protoplasmic poison, in frogs it produces tetanus, convulsions, and paralysis of central origin; in mammals it causes dyspnea, vomiting, trembling, and a slowing of the pulse, with rise of the blood pressure due to stimulation of the respective nerve centers. After death the blood is not coagulable, and the secreting kidney cells are found covered with a crystalline or amorphous mass of a vulpinate. The acid is found also in species of Calycium, Culveraria, Parmelia, and Cyphelium. (Schmidt, Ph. Chemie, St. 1319.) No difference of action exists between vulpinic acid derived from wolf's moss and that synthetically produced. From Cetraria pinastrin Zopf has separated pinastrinic acid, which seems to be very closely allied to vulpinic acid. (Sitzungsb. der Dorpat. Naturforsch.-Gesellschaft, 1892.)

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.