This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Borago hortensis Raii synopf. Buglossum la-tifolium borrago flore caeruleo C. B. Borago officinalis Linn. Borage: a very hairy rough plant, with wrinkled blackish green leaves approaching to an oval shape, and round hollow stalks, on which the leaves are set alternately: on the tops of the branches come forth blue, sometimes red-dish or whitish, monopetalous flowers, each of which is divided into five sharp-pointed seg-ments, and followed by four wrinkled blackish seeds lying naked in the enlarged cup. It is perennial, and grows wild on waste grounds and on old walls.
The leaves of this plant are very juicy, of no smell, and of hardly any particular taste: they seem nevertheless to contain substances of some medicinal activity, though in too small proportion to be sensible till separated from the herbaceous matter. Mr. Boulduc relates, that a decoction of borage leaves, evaporated to the consistence of a syrup, and set by for a few days, yielded saline crystals, partly in form of fine needles, and partly cubical: that the needled crystals were found to be perfect nitre, and the cubical sea salt: that by passing the decoction through quicklime before the infpiffation, both salts were obtained in greater purity and in larger quantity: that the substance of the leaves, remaining after the boiling, being dried and burnt, and the allies elixated with water, the lye, properly evaporated and set to shoot, yielded first a vitriolated tartar, and afterwards sea salt, the liquor, after the crystallization, proving simply alkaline(a). From this analysis it may be pre-sumed, that the aperient and refrigerating virtues, ascribed to borage leaves, are not wholly without foundation; though these virtues are undoubtedly very weak. Malouin remarks, that the juice of the leaves, which is not green, like that of most other herbs, but of a brown colour, added to bitter mixtures of the juices of cresses and chervil, dissipates their bitterness.
The flowers of the plant have been principally made use of, and are generally ranked among the cordials. Medicines may act as cordials, either by virtue of some warmth, pungency, or fragrance; or by a saline quality, abating immoderate heat: but borage flowers seem to have little power of operating in either of these intentions. When fresh, they have a very flight smell, of the agreeable kind, which in drying is lost: to the taste, both the flowers in substance, and an extract made from them by water, are only mucilaginous and sweetish.