This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Caryophylla Aromatica Pharm. Lond. & Edinb. Caryophyllus aromaticus feu potius garyophyllus Pharm. Paris. Cloves: the unripe fruit, or perhaps more properly the cups of the unopened flowers, of a bay-like tree growing in the East Indies; Caryophyllus aromaticus Linn. In shape they somewhat resemble a short thick square nail, of a rusty colour inclining to black: in the inside of each clove are found a stylus, and stamina, with their apices: at the larger end shoot out, from the four angles, four little points like a star; in the middle of which is a round ball, of a lighter colour than the reft, composed of four small scales or leaves, which seem to be the unex-panded petala of the flower. The tree is one of thole, whose flower is produced above the rudiments of the fruit: the ripe fruit, sometimes brought into Europe under the name of antho-phyllus, is marked on the top with the remains of the flower; it is about the size and shape of an olive, and contains, under a thin blackish shell, a hard kernel of the same colour, which has a deep longitudinal seam on one side. The cloves are said to be cured by exposing them to smoke, and afterwards drying them in the fun.
*(a) M. Beaume obtained from six pounds of unbruised caraway seeds, four ounces of essential oil, as colourless as water.
Ol. effent. carui Ph. Lond.
Aqua vel spiritus carui † Ph. Lond. ‡Ph. Ed.
The clove has a strong agreeable smell, and a bitterish, hot, very pungent taste: it is one of the hottest and most acrid of the substances of the aromatic class, and as such is often used, not only internally, but as an external stimulant. The antophyllus has the same kind of flavour with the clove itself; but being far weaker, in smell as well as in taste, it is very rarely applied to any medicinal purposes, and is now scarcely ever to be met with in the shops.
The clove is remarkably disposed to imbibe humidity; and when robbed of its active parts by infusion in menstrua or distillation, and afterwards mixed with fresh cloves, it regains from them a considerable share both of taste and smell. The Dutch, through whose hands this spice is brought to us, have often practised this abuse; which, however, may be easily dis-covered; for those cloves which have once loft their virtue, continue always not only weaker than the rest, but likewise of a much paler colour.
Tinctures of cloves in rectified spirit are of a dark reddish brown colour, of no great smell, but of a highly acrid taste: if the quantity of spirit be considerable, it leaves the clove deprived of all its virtue. On infpiffating the filtered tincture, the spirit, which distills, is found to have very little impregnation from the spice: the remaining extract, nevertheless, does not discover so much smell as the clove in sub-stance, but its taste is excessively pungent and fiery. The quantity of this burning extract amounts to about one third the weight of the clove.
Digested or infused in water, they impregnate the liquor more strongly with their smell than they do spirit, but not near so much with their taste: after repeated infusion in water, they impart still a considerable tincture to rectified spirit. In distillation with water, they give over, very slowly, near one sixth their weight(a) of essential oil; when carefully distilled, colourless; by age, changing to a yellow, and at length to a reddish brown colour; when drawn with a strong fire, proving often of this colour at first; smelling strongly of the cloves; but in taste only moderately pungent, very much less so than the spirituous extract. Neither the remaining clove nor decoction have any considerable taste; the pungency of this spice seeming to depend, not on the volatile or fixt parts separately, but on the combination of the two(a).
(a) Hoffman, Observationes physico-chymica, lib. i.obs. 3.
The oil of cloves commonly met with in the shops, and received from the Dutch, is indeed highly acrimonious: but this oil is plainly not the genuine distilled oil of the clove; for not-withstanding its being more pungent than that which cloves afford by the common process of distillation, it contains a large admixture, oftentimes half its weight or more, of an insipid ex-pressed oil; as appears upon treating it with rectified spirit, which dissolves the pungent aromatic matter, and leaves the gross insipid oil. It is probably from an admixture of the refinous part of the clove, that this sophisticated oil receives both its acrimony and high colour. Fresh cloves are said to yield a high coloured, thick, fragrant oil upon expression: possibly the common oil of cloves, brought from the spice islands, is no other than this oil, diluted with insipid ones. Perhaps the common oil, as being most pungent, is best adapted for some external pur-poses, as the genuine doubtless is for those of an internal aromatic.