This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Berberis seu Oxyacantha galeni. Berberis dumetorum C. B. Berberis vulgaris Linn. Spina acida; Crespinus. Barberry: a large prickly bush, with brittle branches, covered with an ash-coloured bark, under which lies another of a deep yellow; small, smooth, somewhat oval, pale green leaves, finely serrated about the edges, and yellow monopetalous flowers, standing in clusters on the tops upon naked foot-stalks, followed by oblong red berries, containing, each, generally two seeds: some of the individuals have no seeds in their berries, and sometimes berries with and without seeds are found on one bush. It grows wild on chalky hills in several parts of England, flowers in May, and ripens its fruit in September.
The fruit of this shrub is a mild restringent acid, acceptable to the stomach, and of great medicinal efficacy in hot bilious disorders and a colliquative or putrid disposition of the humours. Prosper Alpinus informs us, that the Egyptians employ, in ardent and pestilential fevers and in fluxes, a diluted juice of the berries, prepared by macerating them in about twelve times their quantity of water, for a day or a night, with the addition of a little fennel seed or a piece of bread, and then pressing out and draining the liquor, which is sweetened with sugar, or sugar of roles, or syrup of citrons, and given the patient plentifully to drink: he says he took this medicine himself, with happy success, in a pestilential fever, accompanied with an immoderate bilious diarrhoea(a). Simon Paulli relates, that he was cured of a like disease, by the use of syrup of barberries diluted with water; and that a concrete salt, which he calls tartar, may be obtained from the juice, by mixing two pounds of it with two ounces of lemon juice, digesting them together in a sand-heat for two days, then gently evaporating the filtered liquor to one half, and setting it in a cellar for some days: the tartar, he says, incrustates the sides and bottom of the glass, proves very grateful both to the palate and stomach, and refills febrile heat and the corruption of the humours; from whence it may be presumed to be the essential acid salt of the fruit; by further in-fpiffating the remaining juice, more of this saline substance separates in the same manner. Among us, these berries are commonly made into a gelly, by boiling them with an equal weight of fine sugar, over a gentle fire, to a due consistence, and then straining the fluid through a woollen cloth. By drying the berries, their acidity is abated, and their astringency improved.
The leaves of the barberry bush have likewise a not ungrateful restringent acid taste, and have sometimes been employed in the same intentions as the fruit, as an ingredient in cooling salads. The inner yellow bark, in taste austere and bitterish, is said to be gently purgative, and to be serviceable in jaundices: Mr. Ray commends, in this disease, from his own experience, a decoction in ale or other liquors, or rather an infusion in white wine, of the yellow bark both of the branches and the roots. It gives a deep yellow tincture both to watery and spirituous menstrua.
(a) Alpinus, De medicina aegyptiorum, lib. iv. cap. i.