This section is from the book "Materia Medica And Therapeutics: An Introduction to the National Treatment of Disease", by John Mitchell Bruce. Also available from Amazon: The pharmacology and therapeutics of the materia medica.
Lini Semina - Linseed. - The seeds of Linum usitatissimum, Flax. Cultivated in Britain.
Characters. - Small, oval, pointed, flat, with acute edges, smooth shining brown externally, yellowish-white within, of a mucilaginous oily taste.
Composition. - The seeds of flax contain a quantity of mucilage, chiefly in the testa or coat, and from 1/4 to 1/2 of their weight of the officinal fixed oil. This consists chiefly of the glyceride of linoleic acid, which has a powerful affinity for oxygen, and thus becomes resinoid on exposure, constituting it a "drying oil." The linseed meal, obtained after expression of the oil, consists chiefly of mucilage, proteids, salts, a little oil, but neither starch nor sugar.
Farina Lini. Linseed Meal. Linseed ground and deprived of oil, and the cakes powdered.
From Farina Lini is prepared: a. Cataplasma Lini. - Mix Linseed Meal 4, with boiling Water 10, and add Olive Oil 1/2, stirring constantly.
Freshly bruised linseed is better than the meal and olive oil. Linseed meal is also used in preparing all Cataplasmata except Cataplasma Fermenti.
Infusum Lini. "Linseed Tea," 1 in 30, with Liquorice.
Dose, ad libitum.
Oleum Lini. Brown. Made by expression without heat.
Externally. - Linseed meal is used only as the cataplasma, which is the poultice universally employed to convey heat and moisture to parts, and thus affect the nerves, circulation, and nutrition generally. The oil may be applied to burns, either pure or mixed with an equal quantity of lime-water, constituting carron oil, a substitute for Linimentum Calcis. It may also be used as a laxative in the form of enema.
Internally. - Infusum Lini, or "linseed tea," is a familiar demulcent drink, containing a large quantity of mucilage, which coats the surface of the pharynx and fauces, and thus relieves troublesome throat cough, especially when it is combined with a little stimulant lemon.
Linseed tea is supposed to have a specific and remote local effect as a demulcent on the bronchi and urinary passages, but this is probably referable to the warm water only. It is, perhaps, slightly diuretic as oil of linseed becomes oxydised in the system (as it does on exposure to air), and is excreted by the kidneys as a resinoid body which stimulates these organs.