PART IS.

Materia Medica.

325

This plant is used in Iceland and Lapland as an article ofdiet; being boiled in broth or milk after being freed from itsbitter by repeated maceration in water, or dried and made intobread. It has of late years been brought in considerable quan-tity to tiiis country for medicinal purposes.

Qualities. — The dried lichen differs very little in its appear-ance from the recent plant. It is inodorous, and has a bittermucilaginous taste ; is neither very tough nor very brittle, butis not easily pulverized. When macerated in water it absorbsmore than its own weight of the fluid, and the blisters appearlike little white opake glands, while the other parts of the plantare diaphanous. If the water employed in the maceration bewarm, it acquires a strong bitter taste, very similar to that ofan infusion of quassia. The macerated lichen boiled in wateraffords a yellow-coloured inodorous decoction, which thickensas it cools, and becomes a tremulous jelly, resembling starch,but without any viscidity. After some time this jelly cracks,separates from the watery part, and dries into semi-transparentmasses which are not soluble in cold water, but soluble in boil-ing water; and from which it is again precipitated by infusionof galls. According to the analysis of Proust, 100 parts of li-chen afford 64 parts of a substance insoluble in hot water, some-what resembling vegetable gluten, S3 parts of a matter solublein liot water, resembling starch, and three parts of a bitter ex-tractive principle.*

Medical properties and uses. — Iceland liverwort is tonic, anddemulcent. From some remarks of Linnaeus, made in 1737in the Flora Lapponica, it would appear that the Danish phy-sicians had long before that time employed this lichen, andfound it efficacious in haemoptysis, and pulmonary complaints;but it did not excite the attention of even the continental phy-*sicians, till after Scopoli's observations on it, in 1769, were pub-lished ; and very few years have passed since it was known asa remedy in this country. Its virtues for the cure of phthisishave been very highly extolled; but experience has not alto-gether confirmed the truth of the praises which have been la-vished on it. 2 Its supposed specific effects are said to depend onthe combination of its tonic bitterand its demulcent properties.As a demulcent it is certainly superior to the mucilages; andowing to the bitter principle it contains, its decoction affordsall the good effects that can be obtained from the other demul-cents, and the mucilages, without loading the stomach. It al-lays the tickling cough, and relieves the oppressed breathing;involves the acrid matters contained in the stomach and bowels

I Journal <k Physique, 1806.

» It stiU possesses a high reputation as a remedy for phthisis, by the natives of Ice-land. Mackenzie's Travels, 4to, Appendix, p. 411.