This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
Prepared by exhausting powdered liquorice with ammonia, precipitating by sulphuric acid, redissolving in ammonia, and drying. It forms dark brown or reddish scales, very sweet. It is used for flavouring.
Action and Uses. - Taken into the mouth, liquorice has a sweet taste; it increases the flow of saliva, and being mucilaginous acts as a demulcent. It is used to allay cough by lessening the irritation of the mucous membrane. It is particularly useful when there is violent cough due to irritation of the pharynx and upper part of the respiratory passages (p. 249). It is used as a vehicle to cover the taste of other medicines, and has been used instead of sugar in diabetes. The Pulv. Glyeyr-rhizae Co., which is really a preparation of senna (q.v., p. 909), is a gentle laxative.