This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Glycyrrhiza Pharm. Lond. & Edinb. Glycyrrhiza siliquosa vel germanica C. B. Glycyrrhiza glabra Linn, Liquorice: a plant with oval leaves, set in pairs along a middle rib; and small bluish papilionaceous flowers, standing in spikes, on naked pedicles, at the junctures of the ribs of the upper leaves with the stalk: the flower is followed by a smooth pod containing flat kidney-shaped seeds: the root is very long, slender, flexible, of a brownish colour on the outside and yellow within. It is perennial, a native of the southern parts of Europe, and plentifully cultivated in England: the roots are fit for being taken up in the third year after the flips or offsets have been planted. The liquorice root of our own growth is no wife inferiour to that which is produced in its native climate. The root carefully dried and powdered, is of a richer and more agreeable taste than when fresh, and of a dull yellow colour with a cast of brow]n: the liquorice powder commonly fold is of a weaker taste, and a paler and bright yellow colour, from an admixture probably of other substances.
Liquorice, one of the principal sweets, is almost the only one of the common substances of that class which tends to abate thirst: this property was known to the Greeks, who hence discinguished it, by the name adipson, and employed it, as Galen observes, in hydropic cases, for alleviating the desire of drinking. It is an useful emollient and incraffant in desluxions on the breast, and supposed to prove at the same time gently detergent. Infusions and extracts, made from it, afford likewise very commodious vehicles or intermedia for the exhibition of other medicines: the liquorice taste concealing that of unpalatable drugs more effectually than syrups or any of the sweets of the saccharine kind. It differs also from the sweets of the saccharine or honey kind, from the sweet juices of fruits, and from the sweet matter afforded by the common sorts of grain when beginning to vegetate; in being far less disposed to run into a fermentative state. The cortical part of the root is considerably sweeter than the more compact internal subslance, but the sweet matter appears to be in both of the same kind.
Liquorice root, lightly boiled in a little water, gives out nearly all its sweetness: the decoction, pressed through a strainer, and, after fettling, carefully infpiffated, with a gentle heat, till the matter will no longer flick to the fingers, affords an extract exceedingly sweet, more agreeable than that brought from abroad or prepared among ourselves in the way of business, of a pleasant smell, of a dark reddish brown colour in the mass, and when drawn out into firings, of a golden colour: its quantity amounts to near half the weight of the root. If the liquorice be long boiled, its sweetness is greatly impaired, and the preparation contracts an ungrateful bitterness (a).
* (a) The extract from the first infusion is bronze yellow, exceedingly sweet, without any acrid or bitter relish: - from a second infusion, much deeper coloured, and far lefs agreeable: - afterwards, by coclion, a black acrid extract is obtained, in which the taste of the liquorice can hardly be perceived. Beaume.
Extractum glycyrrhizae Ph. Lond.
Rectified spirit takes up the sweet matter of the liquorice equally with water; and as it dis-solves much less of the insipid mucilaginous substance of the root, the spirituous tinctures and extracts are proportionably sweeter than the watery: they are accompanied also with a flight, but very sensible, pungency. The quantity of spirituous extract amounts only to about one half of the aqueous; and rectified spirit, digested on the aqueous extract, dissolves about one half of it, taking up nearly the whole of its sweetness.