Florentine merchant, about the year 1300, while visiting the Levant. The persons by whom the archil or 
litmus was formerly prepared, being desirous to keep it a secret, gave it the name of tincture of turnsole, pre- 
tending that it was extracted from the turnsole, Heliotropium Europceum. Its nature is now well known in 
this country, and large manufactures of it are carried on in London and Liverpool. The Lichen is imported 
as it is gathered, and is prepared in the following manner: — The plant is first dried, cleansed, and pulverized 
in a mill like the oil-mill. The powder is then thrown into a trough, with one-half its weight of pearlash ; 
is moistened, and then allowed to ferment. This fermentation is kept up for some time, till the colour of 
the materials first changes to a purple red, and then to a blue. In this state it is mixed with a third of its 
weight of very good potash, and spread upon deep wooden trays till dry. A quantity of chalk is added at 
last, apparently for the mere purpose of increasing its weight. It may here be remarked, “that another 
species of Roccella, R. fuciformis, is reported to vie in richness of colouring matter with the common orchel,- 
while the plant attains to a much larger size. This species, like the former, occurs sparingly on the sea 
rocks of the south of Europe ; but it is said to abound in the East Indies, especially on the shores of Su- 
matra, and might deserve the notice of some of our enterprising countrymen.” 
Prepared archil, which has a violet odour, derived from orris root, very readily gives out its colour to 
water, to volatile spirits and alcohol, and is the substance principally made use of for colouring the spirits of 
thermometers. As exposure to the air destroys its colour upon cloth, the exclusion of the air produces a 
like effect in hermetically sealed tubes, the spirits of large thermometers becoming in a few years colourless, 
and the colour being again restored by the admission of air. Archil stains marble in a beautiful manner ; 
and by the addition of a little solution of tin, this drug gives a durable dye of a scarlet colour. 
Medical Properties and Uses. — We know of no medicinal virtues possessed by this lichen, 
though it was employed at one time for relieving pulmonary complaints. It is, however, used in the manu- 
facture of red and blue syrups ; which in the trade are known as syrup of red poppies and syrup of violets. 
Litmus is used in chemistry as a most delicate test, either by staining paper with it, or by infusing it in 
water ; which will presently turn red by acids, and have the blue colour restored by an alkali. 
CETRAKIA ISLAND1CA. 
ICELAND LICHEN, OR ERYNGO-LEAVED LIVERWORT. 
This species of Lichen is a native of the mountainous heaths and woods in the alpine parts of Britain. 
The late Sir J. E. Smith gathered it on the Pentland Hills, near Edinburgh, on Ben Lomond, and in vari- 
ous parts of Scotland. It occurs on all the heaths and mountains on the north of Europe, and Dr. Holland 
informs us that it grows abundantly on the lava on the western coast of Iceland, where the whole plant is 
more luxuriant than with us. Although this Lichen is more or less common in all arctic countries, no 
mention is made of it by Wahlenberg, in his interesting account of the physical distribution of vegetables in 
Lapland. 
Medical Properties. — Iceland moss was first recommended by Linneeus as a popular remedy in 
Sweden, for coughs. Scopoli afterwards published his observations on it, but it excited little attention in 
this country, till Dr. Regnault’s treatise on consumption appeared, in which its virtues were highly extolled. 
According to Bergius, the lichen in its recent state is “eccoprotica,” and when dried, “nutriens, pectoralis.” 
In the Dispensatorium Fuldense, it is said to be “ astringens, roborans, humectans, inviscans, nutriens, 
antiseptica.” It is not, however, used on the Continent, indiscriminately, in every species of phthisis, 
nor in every stage of that disorder. It is chiefly recommended in those instances where the cough is at- 
tended with purulent expectoration; in cases preceded, or accompanied by hiemoptysis; in incipient 
phthisis, when from relaxation there is an increased discharge of mucus from the bronchise; in the sequelae 
of measles, attended by a quick small pulse, pain of the breast, emaciation, violent cough, and purulent ex- 
pectoration. The use of it is forbidden when vomicae are already formed, and proceeding towards ulcera- 
tion ; in dyspnoea, and when there is an increased action of the vessels, with diminished expectoration. 
Neither has the use of Cetraria Islandica been confined to phthisical cases; for it has been recommended in 
malignant fevers, dysentery, and haematemesis. The decoction as ordered by our pharmacopoeias, is so bitter 
as to prevent many persons from taking it ; and when deprived of its disagreeable taste, it can only be 
viewed as a demulcent, and hardly equal in effects to linseed, quince seed, and marsh-mallows. Iceland 
moss certainly does not cure phthisis pulmonalis, but in the last stage of that disease, when solid food is 
oppressive, and the diarrhoea appears to be kept up by the acrid contents of the stomach and bowels ; it 
has appeared to us to check the latter, and to impart both vigour and nourishment to the digestive organs. 
Off. Prep. — Decoctum Lichenis Island. L. E. D. 
