Aqua Laurocerasi.—Cherry-Laurel Water.
Related entry: Laurocerasi Folia.—Cherry-Laurel Leaves
Preparation.—Aqua Laurocerasi is prepared, according to the British Pharmacopoeia (1867), as follows: "Take of fresh leaves of cherry-laurel, 1 pound; water, 2 ½ pints (50 fl℥); chop the leaves, crush them in a mortar, and macerate them in the water for 24 hours; then distill 1 pint (20 fl℥) of liquid; shake the product, filter through paper, and preserve it in a stoppered bottle"—(Br. 1867). The French Codex employs cherry-laurel leaves, ten grammes (10 Gm.) [155 grs.]; water, forty grammes (40 Gm.) [1 oz. av., 180 grs.]; and by a moderate fire distills until fifteen grammes (15 Gm.) [231 grs.] have passed over. The proportion of hydrocyanic acid contained in the cherry-laurel water is determined by means of a titrated solution of cupric sulphate, containing 23.09 Gm. (356 grs.) of this salt, in crystals, to one thousand cubic centimeters (1000 Cc.) [33 fl℥, 391♏] of distilled water. The process is as follows: A flat-bottomed glass beaker is placed upon a sheet of white paper, and 10 Cc. cherry-laurel water, with 1 Cc. of aqua ammoniae, are poured into it. The titrated cupric solution is placed into a burette divided into tenths of a cubic centimeter, from which it is gradually dropped into the liquid in the beaker, and, as soon as the blue coloration is maintained, the number of divisions read upon the burette of the cupric fluid employed, will give exactly, in milligrammes, the proportion of hydrocyanic acid contained in 10 Cc. of the cherry-laurel water experimented with. In this country, cherry-laurel water is often substituted by oil of bitter almond water; as that which is imported is quite variable in strength. In 1875, Mr. W. A. Tilden examined 2 ½ ounces of the oil that rose upon the surface of cherry-laurel water, and concluded that it consisted chiefly of bitter almond oil, accompanied with less than 2 per cent of hydrocyanic acid, a small portion of another volatile oil, and traces of an odorous resin. Mr. Beringer, in 1890, called attention to commercial specimens containing magnesia, undoubtedly due to preparing the water, not by distillation, but by trituration of the essential oil with magnesia and water (Amer. Jour. Pharm., 1890).
Action, Medical Uses, and Dosage.—This water is employed in the same conditions and maladies as those in which hydrocyanic acid is indicated, in doses of from 5 to 30 minims, administered with prudence and caution; but on account of its uncertain strength it is rarely used in this country, bitter almond water being preferred, as it can readily be prepared as wanted for use (see also Aqua Amygdalae Amarae).