Library   

Aromatic Waters are saturated solutions (unless otherwise specified) of volatile oils or other aromatic or volatile substances in distilled water. They are clear and free from solid impurities.

They possess an odor similar to the plant or volatile substance from which they are made, and are free from empyreumatic or foreign odors. Aromatic Waters should be protected from strong light and preferably stored in containers which are stoppered with purified cotton to allow access of some air but to exclude dust.

Aromatic Waters are prepared by one of the following processes U.S.

1. Distillation - Place the odoriferous portion of the plant or drug from which the Aromatic Water is to be prepared in a suitable still with sufficient water, and distil most of the water, carefully avoiding the development of empyreumatic odors through the burning of the substances. Separate any excess of oil, and preserve or use the clear aqueous portion, which should be saturated with the flavoring or aromatic principles of the plant.

2. Solution - The Volatile Oil, or Other Specified Volatile Substance, 2 cc. or 2 Gm.; Distilled Water, a sufficient quantity, to make 1000 cc. Shake the volatile substance with 1000 cc. of distilled water in a capacious bottle, and repeat the shaking several times during a period of about fifteen minutes. Set the mixture aside for twelve hours or over night, filter through paper, and pass enough distilled water through the filter to obtain 1000 cc.

If preferred, the Aromatic Water may be prepared by the above formula but with the addition of about 15 Gm. of purified talc, or a sufficient quantity of purified siliceous earth, or pulped filter paper, with which the volatile substance is thoroughly incorporated. Agitate the mixture well, and filter, returning the first portions of the filtrate until it comes through clear." U.S.

The Distilled Waters hold a much more prominent position in the pharmacy of Europe, particularly of continental Europe, than in that of the United States; and a great deal of thought and elaborate investigation has been bestowed there upon the various conditions calculated to furnish the best products by the most convenient method.

The British Pharmacopoiea (1914) directs the distillation process for the waters, but provides for certain medicated waters the alternative process as follows:

Each of these Waters may be prepared by triturating the corresponding Oil with twice its weight of Calcium Phosphate and five hundred times its volume of Distilled Water and filtering the mixture. In tropical and subtropical parts of the Empire these Aquae Olei may be used in place of the corresponding Aqua of the Text of the Pharmacopoeia Br.

Many vegetable substances impart their peculiar flavor to water distilled from them, and more or less of their medicinal properties. The Distilled Waters chiefly used are those prepared from aromatic plants, the volatile oils of which rise with the aqueous vapor and are condensed with it in the receiver. But as water is capable of holding but a small proportion of the oil in solution, these preparations are generally feeble, and are employed chiefly as pleasant vehicles or corrigents of other medicines.

In the preparation of the Distilled Waters, dried plants are sometimes used, because fresh plants are not to be had at all seasons; but the latter, at least in the instance of herbs and flowers, should be preferred if attainable. Flowers which lose their odor by desiccation may be preserved by incorporating them intimately with one-third of their weight of common salt, and in this state afford Distilled Waters of delicate flavor. Some pharmacists prefer to employ the salted flowers in certain instances, believing that the waters distilled from them keep better than when prepared from the fresh flowers.

It is necessary to observe certain practical rules in conducting the process of distillation. When the substance employed is dry, hard, and fibrous, it should be mechanically divided, and macerated in water for a short time previous to the operation. The quantity of materials should not bear too large a proportion to the capacity of the still, as the water might otherwise boil over into the receiver.

The water should be brought quickly to the state of ebullition, and continued in that state until the end of the process. Care should be taken to leave sufficient water undistilled to cover the whole of the solid matter, lest a portion of the latter, coming in contact with the sides of the vessel, be decomposed by the heat, and yield empyreumatic products. Besides, when the operation is urged too vigorously, or carried too far, a slimy matter is apt to form, which adheres to the sides of the still above the water, and is thus exposed to igneous decomposition.

To obviate these disadvantages, the heat may be applied by means of an oil bath, regulated by a thermometer, or of a bath of solution of calcium chloride, by which any temperature may be obtained between 100� C. and 132.2� C. according to the strength of the solution; or, when the process is conducted on a large scale, by means of steam introduced under pressure into a space around the still termed a "jacketed body."

To prevent the disagreeable effects of charring and the excessive empyreumatic odor frequently noticed in Distilled Waters, caused by the solid contents of the still coming into direct contact with the heated bottom, Remington devised an expedient which prevents the herb from touching the bottom and yet permits the water and steam to have free access to all parts of it. (See Pharmaceutical Still, under Extracta.) A hemispherical No. 12 copper sieve with a handle and loosely fitting lid is filled with the herb and placed in the water in the still. If the bottom of the still be flat or nearly so, the rounded bottom of the cage will have only a very slight point of contact, and thus charring will be prevented.

A convenient mode of applying heat by steam is by means of a coil of metal tubing placed in the bottom of the still, having one end connected with a boiler, and the other passing out beneath or at the side, and furnished with a steam-cock, by which the pressure may be increased or the condensed water drawn off at will.

The best mode of applying heat is generally conceded today to be the direct application of steam, because the Distilled Waters prepared by means of it have a freshness of aroma that is wanting in the others, are always free from the odor of the still, are much more limpid, are less apt to deposit mucilaginous matter, and keep better.

But, however carefully the process may be conducted, the Distilled Waters prepared from plants always have at first an unpleasant smoky odor. They may be freed from this by exposure for a short time to the air before being enclosed in well-stoppered bottles, in which they should be preserved. When long kept, a viscid ropy matter is apt to form in them from the growth of micro-organisms and they lose their characteristic flavor and odor. To prevent this decomposition, a little alcohol is sometimes added to the water employed in its distillation.

But this addition is inadequate, and is in fact injurious, as the alcohol by long exposure to the air undergoes the acetous fermentation. A better plan is to redistill the Waters. When thus purified, it is said that they may be kept for several years unchanged.

Another mode of preparing the Distilled Waters is to substitute the volatile oil, previously separated from the plant, for the plant itself in the process. This mode is directed in the British Pharmacopoeia in several instances. It is said to afford a more permanent product than the preceding, but does not always preserve the flavor of the plant.

The U.S. Pharmacopoeia X recognizes for the making of Aromatic Waters only the process of dissolving the separated volatile oil. In former editions the oil was directed to be triturated with some insoluble powder, which aids in the solution of the oil by causing its division into very small particles; the powder impregnated with the oil was then shaken with water and filtered.

Magnesium carbonate was at one time used for the dispersing substance, but although it produces a water that has a fine flavor and appearance, the alkalinity imparted makes it unsuitable for many purposes. Among the various other substances that have been suggested for this purpose may be mentioned calcium phosphate (U.S.1850), talcum (N. F., 1888), kieselguhr (La Wall, Proc. N. J. Ph. A., 1908) and absorbent cotton (U.S. 1880). Thum (Proc. Pa. Ph. d., 1916, p. 225) showed that for the use of these an intervening filtering agent was unnecessary and the U.S.P. X recommends simple agitation with cold water, a period of maceration and subsequent filtration.

As alternative processes, purified talc, purified siliceous earth or pulped filter paper are permitted as distributing media. A very good way to make medicated waters when a volatile oil is directed, is that proposed by Percival, which is to heat the water required, pour it into a bottle and add the oil, cork tightly, shake occasionally until cool, then pour off and filter; this secures a medicated water free from foreign substances, and a saturated solution, most oils being more soluble in hot than in cold water.

The Dublin College prepared its Waters by agitating an alcoholic solution of the oil with distilled water, and filtering. They consequently contained alcohol, and were liable to objection in this account. In the preparation of the aromatic waters by these processes, it is very important that distilled water should be used, for tap water frequently contains constituents which have a deteriorating effect upon the aroma of the water.

The Distilled Waters are liable to contain various metallic impurities, derived from the vessels in which they are prepared or preserved. The metallic salts which have been found in them are those of iron, zinc, copper, and lead. With potassium ferrocyanide, iron will give a blue color, zinc and lead white precipitates, and copper a rose color followed by a chestnut brown precipitate. Sodium sulphide causes with salts of iron, copper, or lead, a brown discoloration more or less deep, followed by precipitates varying from brown to black; with those of zinc a white precipitate.