Achillea millefolium. Yarrow.
Nat. Ord. — Asteraceae. Sex. Syst. — Syngenesia Superflua.
Description. — Yarrow, also called Milfoil, is from twelve to eighteen inches high, with simple stems,, branching at top. The leaves are doubly pinnate, crowded, alternate, with linear, dentate, mucronate segments. The flowers are white or rose-colored, and are arranged in a dense, flat-topped, compound corymb ; involucre oblong and imbricated. Rays four or five, short ; receptacle chaffy, small, flattish. Achenium oblong, flattened, margined.
History. — Yarrow is a perennial herb, common to Europe and North America, growing in fields, woods, pastures, etc., and flowering nearly the whole summer. The American plant is the most active. The flowers and leaves have an agreeable, but feeble aromatic odor, and a bitter, astringent, pungent taste. It contains a volatile oil, bitter extractive, tannin, and achilleic acid. The active principles are extracted both by water and alcohol.
According to M. Zanon, the active principle of this plant, Achilleine, has been used as a substitute for sulphate of quinia in intermittent fevers, in the south of Europe. It is prepared by boiling five pounds of the dried plant with sixteen pounds of rain-water for about two hours. The residue is again boiled twice with smaller quantities of water, the decoctions are then filtered and mixed. These are then clarified with white of egg, and evaporated at a gentle heat until a whitish pellicle is formed on the surface. After twenty-four hours the cold liquid deposits a mass consisting for the most part of vegetable fiber, green coloring substance, with some coagulated albumen, extractive matter insoluble in alcohol, lime-salts, and traces of silica. The bitter and acid liquid is filtered, and then treated with an excess of hydrate of lime, which produces a white precipitate; upon this the liquid is treated with acetate of lead as long as any precipitate is formed. This precipitate is collected on a filter, and the solution saturated with sulphureted hydrogen, after which it still possesses a yellowish color and a very bitter taste. On evaporation it yields nearly half a pound of dry extract, which, as well as the previously-filtered sulphuret of lead, are exhausted with alcohol. The two, mixed and evaporated, yield about seven ounces of achilleine.
The achilleine obtained in this manner, contains some acetate of lime, resin, etc., but which may be avoided by treating the neutralized decoction (above, by hydrate of lime) with animal charcoal, then evaporating to dryness, and finally extracting with boiling absolute alcohol.
The color of achilleine is instantly destroyed by chlorine ; it is not precipitated by tincture of galls nor acetate of lead, but it is thrown down by basic acetate of lead ; it is soluble in ammonia, and the solution, when exposed to the air until the ammoniacal odor has disappeared, deposits brown flakes, which are less soluble than achilleine ; the slight trace of resin in achilleine may be removed by solution in water.
Achilleic acid is obtained by treating the decoction of Yarrow with acetate of lead as long as any precipitate is formed, this is suspended in water, and decomposed with sulphureted hydrogen. The liquid obtained will be very acid, and contain some lime and green coloring substance ; to precipitate the lime, supersaturate it with carbonate of potassa, and then treat it with animal charcoal. The potassa-salt may be precipitated with acetate of lead, and the precipitate decomposed with sulphureted hydrogen.
Achilleic acid is not volatile at 212° F. ; its solution can therefore be concentrated by evaporation in the water-bath. The greatest concentration to which it can be brought is 1.014825. In this state it is perfectly colorless, but on further evaporation it becomes straw-colored. Exposed to the air in a glass or porcelain dish, it crystallizes in perfectly colorless quadrilateral prisms. The crystallized acid requires at 56° F. two parts of cold water for solution ; the solution is very acid, makes the teeth rough, has no odor, and strongly reddens litmus paper. Added by drops to a clear solution of acetate of lead, it does not render it in the least turbid ; but in a solution of basic acetate of lead it immediately produces a white precipitate, which is very slightly soluble.
Achilleic acid forms salts with carbonates of potassa and soda, ammonia, lime, magnesia, and quinia, which may become useful therapeutical agents. The achilleate of quinia is very soluble, and may be found superior to the sulphate of quinia; it may be made by dissolving quinia in very slightly-diluted acid, allowing the substances to act on each other for several days, stirring them frequently, until the liquid no longer reddens litmus paper. Then filter, and add some alcohol; heat it nearly to boiling, and allow it to cool, when nearly the whole liquid is converted into very beautiful radiate-grouped prismatic crystals, which are very bitter, and readily soluble in water or alcohol.
Properties and Uses. — Yarrow is a tonic, astringent, and alterative. It has been used in intermittent fever, hemoptysis, hematuria, incontinence of urine, diabetes, hemorrhoids, and dysentery ; also in leucorrhea, amenorrhea, flatulent colic, and some nervous affections. In menorrhagia, half a fluidounce of the saturated tincture, repeated three or four times daily, has been found advantageous ; a few drops of oil of anise will cover its unpleasant taste. The late Prof. T. V. Morrow made much use of an infusion of this herb in dysentery. Dose of the infusion, from four to six fluid ounces, three or four times daily ; of the volatile oil, from ten to thirty drops.
Achillea Ptarmica or Sneezewort, grows in hedges and thickets, and in moist places in various parts of the country. It is about two feet in hight, with the leaves sessile, linear or slightly lanceolate, acuminate, equally and sharply serrate, with appressed teeth, and smooth. The flowers are white, and arranged at the top of the plant in a diffuse corymb. The leaves are remarkably distinct from the Yarrow. The whole plant is pungent, exciting an increased flow of saliva. The powder of the dried leaves when snuffed into the nostrils, produces sneezing, which is supposed to be owing to their small, sharp, and marginal teeth.