This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Hyssopus Pharm. Edinb. Hyssopus offici-narum caerulea five spicata C. B. Hyssopus officinalis Linn. Hyssop: a low shrubby plant; with brittle branched stalks, square when young, and round wheh they grow woody; oblong narrow dark green leaves set in pairs; and loose spikes of labiated blue flowers, whose upper lip is cloven and turned upwards, (landing in rows, towards the tops of the stalks, generally all on one side, in long striated cups. It is perennial, cultivated in gardens, and flowers in July and August.
The leaves of hyssop have an aromatic smell, and a bitterish moderately warm taste. They give out their active matter both to water and rectisied spirit, to the last mod perfectly: the watery infusions are of a brownish or greenish yellow, the spirituous tinctures of a dark black-ifh green colour. On infpiffating the spirituous tincture, very little of the flavour of the herb exhales or distils with the menstruum: the remaining extract is bitterish and very warm, and discovers a penetrating pungency, somewhat like that of camphor. Water, distilled from the fresh herb, is found pretty strongly impregnated with its flavour: an essential oil separates and rises to the surface, to the quantity of about an ounce from six pounds of the leaves, in smell exactly resembling the hyssop, in taste very pungent, in colour, when newly distilled, yellowish with a flight cast of green, which by age changes to a brownish: the decoction, remaining after the distillation, is disagreeably roughish, bitter-ish, and subsaline.
This plant is accounted particularly service-able, as an attenuant, corroborant, and expecto-rant, in humoural asthmas, coughs, and other dis-orders of the breast and stomach unaccompanied with inflammatory symptoms: in these cases, infusions of the leaves, which are not unpala-sable, may be sweetened with honey or sugar, and drank as tea. The distilled water, by some made choice of as a basis for pectoral mixtures and juleps, does not appear superiour or equal to the infusion.