_Iceland Liverwort._ _Iceland Moss._
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.