This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Hypericum Pharm. Lond. Hypericum vul-gare C. B. Androsaemum five perforata Gesn. Hypericum perforatum Linn. St. John's wort: a plant with slender round woody reddish stalks, which have two fine ridges, or sharp edgings, opposite, alternately, from joint to joint; small oblong obtuse leaves, set in pairs without pedicles; and numerous gold-coloured pentapetalous flowers on the tops of the branches, followed by little rough blackish husks, each of which is divided into three cells full of minute seeds. It is perennial, grows wild in woods and uncultivated places, and flowers in June and July.
This plant has been recommended as a medicine of peculiar efficacy in hysterical and hypochondriacal disorders, and alienations of mind; from its supposed virtue in which cases, it received the name offuga damonum. It promises to be of some use as a mild detergent and corroborant, discovering to the senses a resinous, bitter-iiri, balsamic impregnation. The leaves, viewed against the light, exhibit numerous transparent points, which are found to be little vesicles full of esiential oil or resinous matter; in distillation with water, the oil separates and rises to the surface, approaching in some degree to that of turpentine. About the edges of the flower are observed black points, and on the seed vessels small tubercles, which appear to be similar oily vesicles: the tops, when the seeds are formed, have the strongest terebinthinate smell, and yield in distillation the greatest quantity of oil. The flowery tops give a deep yellowish red tincture to rectisied spirit, and a paler red to expressed oils: this colour does not appear to proceed from the sub-stance of the leaves or flowers, but from the re-finous juice in the vesicles above-mentioned. A tincture of the flowers in oil olive, made by macerating four ounces of the full blown flowers, fresh gathered, and freed from the cups, in a quart of oil, till the oil is sufficiently coloured, is kept for external purposes in the shops, but very rarely made use of.
Succ. spissat. Hyoscyam. Ph. Ed.