Qualities. Odour, none; Taste, mucilaginous and bitter. Solubility. The effect of water upon this vegetable substance is materially modified by temperature; if cold, the lichen absorbs nearly its own weight by maceration, but gives out to the menstruum little or none of its virtues; if the water be warm, it soon acquires a bitter impregnation; by ebullition, a decoction is obtained, which, as it cools, gelatinizes. See Decoct. Lichen. Chemical Composition. Proust has shewn by analysis that 100 parts of this moss contain 64 parts of a substance bearing some analogy to vegetable gluten, 33 of matter, soluble in hot water, and resembling starch, and 3 parts of a bitter principle. Medicinal Uses. This vegetable was introduced to the notice of the profession by Linnæus, who recommended its decoction, as having been administered with great success for coughs in Sweden. Upon its introduction into this country, its patrons bestowed so many extravagant eulogiums upon its powers, that the less sanguine practitioner at once abandoned its use in disgust, and it fell into unmerited disrepute. It would be idle to speak of its specific effects in phthisis; but, as a demulcent, it is certainly very superior to the mucilaginous mixtures in ordinary use, and its simple bitter principle at the same time tends to produce a tonic effect, which is frequently desirable in the debilitated condition which characterizes the latter stages of this disease. There are circumstances, however, which may render the removal of the bitter advantageous; in which case, maceration in successive waters, or in a weak alkaline ley, as recommended by Westring, will be found to answer the intended purpose. Officinal Preparation. Decoct. Lichen. Island. E. D. Sir Alexander Crichton has offered some observations upon the genuineness of this article which deserve attention. He says that there are two varieties in the market; the best of which has a horny texture, and yields a bitter mucilage. It is that which comes from Iceland, Norway, Sweden, and Finland. The inferior kind has a membranous texture, and yields little bitter or mucilage in comparison with the former. Where it comes from he knows not, but he suspects it to be British, as it is much cheaper than the other.
LIMONES. L.E.D. (Citrus Medica. Baccæ.)
Lemons.
Succus—The Juice consists of Citric acid, mucilage, extractive matter, and small portions of sugar and water. Specific gravity, 1·0384. It may be preserved for a considerable length of time, by covering its surface with fixed oil.
Its use in making saline draughts has been already noticed, see Acid. Citric. Its principal medicinal value consists in its antiscorbutic[[549]] virtues; indeed it may be fairly asserted that this disease, so peculiarly incident to a sea life, has been nearly eradicated by the juice of lemons. Sir Gilbert Blane, in speaking of its efficacy, asserts that “those only who have made themselves acquainted with the early part of the Naval history of this country, or those who have perused the interesting, popular, and eloquent narrative of Commodore Anson’s voyage, can duly appreciate the value of this simple remedy.” Lemonade, as a beverage in putrid diseases, was first introduced by the French physicians in the beginning of the 17th century, and about the year 1660, an Italian from Florence, having learnt a process of freezing confectionary, conceived the happy idea of converting such beverage into ice. This found a ready sale, and was the occasion of so great an increase in the number of sellers of Lemonade, that in the year 1676, the Lemonadiers of Paris were formed into a company, and received a patent from the government.
Cortex—The Rind or Peel is composed of two distinct parts; the exterior, which contains glands, filled with a fragrant volatile oil, upon which all its properties depend, and the interior coat, which is tasteless and indigestible. The flavour may be obtained by rubbing lump sugar upon it, which will imbibe the oil, and if it be then dried by a very gentle heat, may be preserved unimpaired for any length of time, and will be preferable to the volatile oil obtained by distillation, for the fire generally imparts an unpleasant or empyreumatic flavour.[[550]]
It has been already stated, that “the different parts of the same plant have frequently very different properties.” The Lemon offers a good example of this fact, for its juice is acid, its seeds bitter, and its peel aromatic.
LINIMENTA. L.E.D. Liniments.
These are external applications, having the consistence of oil or balsam. If we except the Liniment. Æruginis, all the officinal liniments are decomposed by the substances which are incompatible with soaps.
Linimentum Æruginis. L. Oxymel Æruginis. P.L. 1787. Mel Ægyptiacum. P.L. 1745. Unguentum Ægyptiacum. P.L. 1720. Diluted with water, it has been recommended as a gargle in venereal ulcerations, but its use is hazardous; it is a detergent escharotic preparation.