Under the title of Aqua Laurocerasi (Cherry Laurel Water), a preparation of similar nature is official in several pharmacopoeias. It is made by distilling a mixture of bruised fresh laurel leaves and water. This preparation is likewise standardized to a definite percentage of hydrocyanic acid. The Spanish, German, Greek, and Swiss pharmacopoeias substitute the above-mentioned bitter almond water for cherry laurel water. The German Pharmacopoeia prepares a diluted bitter almond water (Aqua Cerasorum or Kirschwasser), by mixing 1 part of the stronger with 19 parts of water. This preparation, containing 0.005 per cent. of hydrocyanic acid, should not be confounded with either of the above containing 0.1 per cent. of the acid. AQUA CHLOROFORMI.-Chloroform is added in sufficient quantity to distilled water, so that, after agitation, it remains in slight excess; the supernatant saturated solution is decanted off as required. When exposed to sunlight, the chloroform readily undergoes decomposition, particularly so in the presence of water. Hence this preparation should be kept in a dark amber-colored bottle. It is employed as a solvent for many remedies, owing to its preservative properties; also, as an adjunct to anodyne mixtures. AQUA CREOSOTI.-This preparation contains 1 per cent. of wood creosote. It is employed principally as a gargle, or lotion. In ordering creosote, care should be taken to specify "true wood creosote," or "beech-wood tar creosote," for under the term " commercial creosote" carbolic acid is usually understood. Under the class of Aquæ, solutions of gases are included, viz. :— AQUA AMMONIÆ. (Specific gravity 0.960, containing 10 per cent. by weight of gaseous ammonia (NH3).) It is known among the continental pharmacopoeias under the title of "Liquor Ammonia," being generally recognized to be of 10 per cent. strength (Fr. and Sp., 20 per cent.) This is commercially known as 16° Baumé; the so-called Aqua Ammoniæ f.f.f., being 20° B., or about 17 per cent. by weight of NH3. AQUA AMMONIE FORTIOR (sp. gr. 0.901, containing 28 per cent. by weight of gas), is only recognized by the U. S. and British Pharmacopoeias, that of the latter, however, being of 32.5 per cent. strength. For rules for dilution, see page 138. Ammonia Water is incompatible with acids and most metallic salts; it should be preserved in well stoppered bottles in a cool place. Its strength is ascertained by means of its specific gravity, or by titration with a standard acid solution.* 2NH, Ammonia. 2 X 17 pts. 17 pts. + H2SO Sulphuric Acid. 97.82 pts. 48.91 pts. 0.0489 pt. = (NH,),SO. Ammonium Sulphate. Since 1 Cc. of decinormal sulphuric acid solution (containing 0.0489 Gm. H2SO4) neutralizes 0.017 Gm. of ammonia gas (NH3), 20 Cc. of the acid solution will be equivalent to 20 × 0.017 0.34 Gm. of NH3. If 3.4 Gm. of Aqua Ammonia were taken for the assay, it would then, according to the above, contain 10 per cent. of ammonia gas. - 2 AQUA CHLORI.-A clear, greenish-yellow liquid, containing at least 0.4 per cent. of chlorine gas, U. S. P. This preparation is official in all pharmacopoeias, and contains from 0.3 to 0.6 per cent. of chlorine gas. It should be freshly prepared when required for use, since it rapidly undergoes decomposition; thus, 2CÎ + H2O = 2HCl + 0. As a ready means of ascertaining whether this decomposition has begun, or not, the pharmacopoeia directs agitation of the sample with mercury, which unites with the free chlorine, leaving any hydrochloric acid which may be present free to be detected by litmus paper. Chlorine water is employed in medicine as an antiseptic. It is incompatible with alkalies, silver and lead salts, tannin, infusions, emulsions, and tinctures, and liberates iodine and bromine from their salts. When prescribed in mixtures it should be added last. The chlorine strength of this preparation is ascertained indirectly by volumetric estimation. This is based on the fact that chlorine displaces an equivalent amount of iodine from potassium iodide, according to the equation: The liberated iodine is held in solution by the excess of potassium iodide. In order to ascertain the amount of liberated iodine, decinormal solution of sodium hyposulphite is run into this dark-colored solution until it is decolorized, according to the following equation: Since 1 Cc. of decinormal solution of sodium hyposulphite containing 0.0247 Gm. of the salt, is equivalent to 0.01265 Gm. of iodine, therefore 20 Cc. of the hyposulphite solution will be equivalent to 20 X 0.01265 = 0.253 Gm. of iodine. Hence if one molecule of iodine is equivalent to one molecule of chlorine, 0.253 Gm. of iodine will be equivalent to x grammes of chlorine. That is, If 17.7 Gm. of Aqua Chlori, after having been subjected to the above test, yield 0.070 Gm. of chlorine, it would then contain of the gas 17.7 0.07: 100 x; x = 0.4 per cent. (approximately). AQUA HYDROGENII DIOXIDI.—This solution should contain 3 per cent. by weight of the pure Dioxide (H2O2), corresponding to about 10 volumes of available oxygen. The dioxide itself may be obtained in a very pure condition* by agitating barium peroxide with diluted hydrochloric acid and ether, the latter absorbing the H2O2; upon shaking the ethereal solution with distilled water, slightly acidulated, it gives up most of its hydrogen peroxide. The great facility with which this solution gives up its oxygen renders it a powerful oxidizer. It bleaches organic colors, likewise hair; converts sulphides and sulphites into sulphates, ferrous into ferric compounds; liberates chlorine from hydrochloric acid, iodine from hydriodic acid, and iodide of iron; it reacts very slowly in a neutral solution of potassium iodide, thus differing from ozone and chlorine. It is stated that the addition of one part of H2O2 to 1000 parts of impure drinking water will, after a short time, effectually destroy any disease germs that may be present. It is employed in medicine as a powerful antiseptic, and deodorant. The presence of a little acid (even as little as one drop of HCl to the pint), is essential to prevent its too rapid decomposition. The commercial solution scarcely ever contains over three per cent by weight of absolute peroxide, and the ten and fifteen volume solutions often fall short of the strength claimed for them; hence it behooves the apothecary to assay each lot which he may purchase. The strength of this solution is sometimes indicated by volume. Thus a 20 volume solution is one which, when decomposed into water and oxygen, will yield 20 times its volume of oxygen. It does not matter, in this case, whether the whole of the liberated oxygen comes from the H2O2, or whether a part of this comes from the reagent added. If the H2O2 is decomposed by potassium permanganate, only one-half of the oxygen given off comes from the H2O2. The strength of the solution is estimated by means of decinormal * Cresiner," Proceed. A. P. A.," 1892, p. 845. solution of potassium permanganate * according to the following equation: KMnO + = Hydrogen 5H2O2+ 3H2SO 50, +8H0 + K2SO、 + 2MnSO, Potassium Permanganate. 315.3 Peroxide. The permanganate solution is added slowly, until the pink color no longer disappears. The presence of the sulphuric acid serves the purpose of dissolving the manganic hydroxide as fast as formed, otherwise the brown oxide diffused through the liquid. would render the end of the reaction difficult to distinguish. Now, according to the above equation, 1 mol. of K,Mn2O, (315.3 p.) corresponds to 5H2O2 (169.6 p.); or 0.003153 Gm. of potassium permanganate (1 Cc. of the decinormal solution), corresponds to 0.001696 Gm. of absolute hydrogen peroxide. Where it is desirable to express the strength in volumes of available oxygen, we multiply the number of cubic centimeters of the solution of permanganate, decolorized by 1 Cc. of the solution, by 0.56. This latter factor is explained thus: 80 315.3 Since one-half of the liberated oxygen is supplied by the potassium permanganate (K,Mn2O), one molecule of KMnO liberates 5 of oxygen from the hydrogen peroxide (H2O2); hence, 63 Gm. of K2Mn2O, (one-fifth of 315.3) will liberate 16 Gm. of oxygen (one-fifth of 80), which at normal temperature measures 11,188 Cc. If 63 Gm. of potassium permanganate liberate 11,188 Cc. of oxygen, 0.00315 Gm. of permanganate (1 Cc.) will liberate 0.56 Cc. of oxygen. * See Decinormal Solution of Potassium Permanganate. + The substance precipitated (from alkaline solution) is manganous hydroxide, which rapidly turns to brown manganic hydroxide In In this and subsequent tables (per cent.) is employed merely as an expression of convenience. In the case of anise water and others of this class, it means 2 Cc. of the oil in 1000 Ce. of water. the case of camphor water it means 8 Gm. of Camphor in 1000 Cc. See "Percentage Solutions," page 137. Aqua Aurantii Florum, Equal parts of the above and Vehicle. distilled water. Triple Rose Water. Equal parts of the above and Vehicle. INJECTIONES HYPODERMICE (Hypodermic Injections). When remedies are to be used hypodermically, it is absolutely necessary that these solutions be as neutral as possible and sterilized. As antiseptic vehicles, for the administration of these remedies, various solutions have been proposed, such as solutions of camphor, thymol, or corrosive sublimate, and chloroform water; however, when these solutions have been exposed to the air, they are not fit to be dispensed. When it is necessary to prepare such a solution, the test-tube in which it is prepared and the receiving vessel, should be first sterilized by rinsing them with boiling water, and then dried in an oven at a temperature of about 200° C. Only thoroughly boiled distilled water should be used as solvent. In Germany and Austria, these solutions are now often prepared and sealed in small, elongated glass pearls (sterilized at 200° C.) of 1 Cc. capacity. Thus sealed, these solutions may be preserved indefinitely and can be readily carried about. The sterilized hypodermic tablets, in which exsiccated neutral sodium sulphate forms the inert diluent, have become very popular, because of their convenience in use, and the accuracy of their dosage. These tablets should always be dispensed in their tubes and never handled with the fingers. The hypodermic dose of a remedy is or less than the dose by the mouth. |