This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Rosmarinus Pharm. Lond. & Edinb. Rosmarinus hortenfis angustiore folio C. B. Liba-notis corcnaria quorundam. Rofmarinus officinalis Linn. Rosemary: a large shrubby plant, clothed with long narrow stiff leaves, set in pairs, of a dark green colour above and hoary underneath; producing pale bluish labiated flowers, which stand in clusters round the stalk in the bosoms of the leaves. It is a native of the sou-thern parts of Europe, common in our gardens, and seems to grow larger and more woody in this than in molt other countries. It flowers in April and May, and sometimes again about the end of August.
Rosemary is a warm pungent aromatic; particularly useful in phlegmatic habits and debilities of the nervous system; of the same general nature with lavender, but with more of a camphorated kind of pungency, and of a stronger, and to rnost people less grateful, smell. The render tops are the strongest both in smell and taste, and next to these the cups of the flowers; which last, though somewhat weaker than the leaves or tops, are nevertheless the most plea-sant, and hence are generally preferred: it is chiefly, if not wholly, in the cup, that the active matter of the flower resides; for the bluish petalum, carefully separated, has very little smell or taste. The fragrance of these flowers is greatly diminished, or in great measure de-stroyed, by bruising or beating; and hence the officinal conserve, formerly made by beating them with thrice their weight of sugar, had very little of the flavour of the rosemary.
The leaves and tops of rosemary give out their virtues completely to rectified spirit, but only partially to water: the spirituous tinctures are of a yellowish green colour, the aqueous of a dark greenish brown. Distilled with water, they yield a thin, light, pale coloured essential oil, inclining a little to yellowish or greenish, of great fragrancy, though not quite so agreeable as the rosemary itself: from one hundred pounds of the herb in flower were obtained eight ounces of oil: the decoction, thus diverted of the aromatic part of the plant, yields on being infpiffated an unpleasant weakly bitterish extract. Rectified spirit likewise, distilled from rosemary leaves, becomes considerably impregnated with their fragrance, leaving however in the extract the greatest share both of their flavour and pungency. The active matter of the flowers is somewhat more volatile than that of the leaves, greatest part of it arising with spirit. The Hungary water, used as a perfume, and sometimes medicinally in nervous complaints, and which is said to have received its name from its being first made public by an empress of that nation who was cured by its continued use of a paralytic disorder, is a strong spirit distilled from fresh rosemary flowers: the college of Edinburgh directs a gallon of rectified spirit to be drawn over in the heat of a water bath from two pounds of the flowers as soon as they are gathered†: that of London takes the tops, and a spirit not quite so strong; putting a gallon of proof spirit to a pound and a half of the fresh tops, and drawing off in the heat of a water bath five pints‡. The hungary water brought from France is more fragrant than such as is generally prepared among us.