genated oils lies, as a rule, in the oxygenized compounds which they contain, and which are present in the different oils in proportions varying from 1 to 90 per cent. By producing these synthetically, artificial oils, identical with the natural, have been made, of which the official methyl salicylate or artificial oil of wintergreen (identical also with the natural oil of sweet birch) is an example. The Pharmacopoeia recognizes a single concrete volatile oil, camphor, which can be appropriately classed among the oxygenated oils, since its chemical composition shows it to be a pure oxidized hydrocarbon. The official oxygenated oils are those of anise, bergamot, betula, cajeput, caraway, cloves, chenopodium, cinnamon, coriander, eucalyptus, fennel, gaultheria, hedeoma, lavender flowers, lemon, orange flowers, orange peel, peppermint, spearmint, myrcia, nutmeg, pimenta, rose, rosemary, santal, sassafras, and thyme. Of these, the oils of bergamot, orange peel, and orange flower consist almost entirely of limonene, one of the isomeric terpenes, containing less than 3 per cent. of undetermined oxygenated bodies. 3. Nitrogenated Oils. Some plants do not produce volatile oils in nature, but contain certain principles which, in the presence of water, react upon each other, causing the formation of new compounds, one of which is a volatile oil; such is the case with certain plants belonging to the natural order Rosacea, sub-order Amygdala. The volatile oil, when absolutely pure, contains no nitrogen, but the name nitrogenated oils has been given to this class because in their formation they are always accompanied by a nitrogenized substance, hydrocyanic acid, which is present in variable proportion and which lends to the oils their poisonous character. The only official nitrogenated oil is the oil of bitter almond, which is prepared by mixing freshly powdered bitter almonds with the residue left after expressing the fixed oil from bitter and sweet almonds, adding water, and distilling at a moderate heat. The specific gravity of the oil ranges from 1.060 to 1.070 at 15° C. (59° F.), and that of the purified oil is about 1.045. The oil is sometimes adulterated with nitrobenzene or artificial oil made from toluene. Bitter almonds, like peach and cherry seeds, contain both the albuminous ferment and the peculiar compound, amygdalin, necessary for the reaction, while sweet almonds. contain only the ferment, and hence will yield no volatile oil unless mixed with the bitter variety. The hydrocyanic acid present in oil of bitter almond sometimes amounts to as much as 6 or 7 per cent., and may be removed by shaking the oil with ferrous chloride and lime-water and then rectifying by distillation. Oil of bitter almond is soluble in 300 parts of water and in all proportions of alcohol. 4. Sulphuretted Oils. Like the preceding class, these oils are the result of fermentative action, in which the living plant takes no part except to provide the necessary active principles for the subsequent reaction in the presence of water. Sulphur is present in the oils, combined with certain organic radicles, in the form of sulphide or sulphocyanate. Nearly all the oils of this class are obtained from members of the natural order Cruciferæ. The Pharmacopoeia recognizes but one sulphuretted oil, namely, the volatile oil of mustard, made from black mustard seed, which has a specific gravity varying from 1.018 to 1.029 at 15° C. (59° F.) When shaken with alcohol and ammonia water and slightly warmed, the oil deposits crystals of thiosinamine; 3 Gm. of oil should yield not less than 3.25 Gm. nor more than 3.5 Gm. of such crystals. 5. Empyreumatic Oils. Among the products of destructive distillation are certain volatile oils, which are characterized by a peculiar tarry odor, an acid reaction and a somewhat bitter taste. They are lighter than water, sparingly soluble in that liquid, but readily soluble in alcohol. Oil of cade and oil of tar are the only empyreumatic oils recognized in the Pharmacopoeia; the former is obtained by the dry distillation of the wood of the prickly cedar (juniperus oxycedrus) and the latter by distillation of tar. PART II. PRACTICAL PHARMACY. THE study of practical pharmacy involves both galenical and extemporaneous pharmacy, the former pertaining to the various preparations of drugs, the latter to the many operations of the dispensing counter. The different classes of plant products used in medicine, as well as the various methods of solution and separation, have been considered in previous chapters; the numerous preparations of drugs will be treated after a plan which, for a number of years, has proven satisfactory to students, and although not based on a strictly symmetrical arrangement, is probably in keeping with the advance made by them in other branches of study up to this point. The official preparations may be divided into those of a strictly pharmaceutical character and those involving chemical action; the latter class will be considered under the head of pharmaceutical chemistry, where the preparations of each element or compound will be grouped together. The galenical preparations of the Pharmacopoeia may be classified as follows: 1, Waters; 2, Solutions or Liquors; 3, Decoctions and Infusions; 4, Syrups; 5, Mucilages, Honeys, and Glycerites; 6, Elixirs; 7, Spirits; 8, Tinctures; 9, Wines and Vinegars; 10, Fluid Extracts; 11, Extracts; 12, Oleoresins and Resins; 13, Collodions; 14, Emulsions; 15, Mixtures; 16, Pills; 17, Lozenges and Confections; 18, Powders and Triturations; 19, Granular Effervescent Salts; 20, Cerates and Ointments; 21, Liniments and Oleates; 22, Plasters and Suppositories. The operations of the dispensing counter are intimately associated with the various preparations of drugs officially recognized, and, instead of treating them separately under a special head, it is thought most convenient to consider them in connection with some of the subdivisions named above, particularly as eight classes of the official galenical preparations require remarks and explanations, which apply equally to the details of dispensing pharmacy. Certain forms of administering medicines, not as yet recognized in the Pharmacopoeia, but which, of late years, have come into use extensively, such as Compressed Tablets, Tablet Triturates, Hypodermic Tablets, Medicated Disks, etc., may be looked upon as modifications of the official class of lozenges and studied in connection with these. CHAPTER XIII. THE OFFICIAL WATERS. THE official waters include common and distilled water, as well as those known as medicated waters; the latter are all solutions of volatile substances, and were it not for this pharmacopoeial classification, four of them might be considered as more appropriately belonging to the class of liquors or solutions proper, instead of medicated waters, namely, aqua ammonia, aqua ammoniæ fortior, aqua chlori, and aqua hydrogenii dioxidi. The U. S. Pharmacopoeia directs three different methods for the preparation of medicated waters; namely, by simple agitation of the medicinal ingredient with cold water, by trituration of essential oils with precipitated calcium phosphate and water, and by distillation. In England and Germany the second method is not practised, the pharmacopoeias of both countries directing all aromatic waters to be made by distillation. Another excellent method for making aromatic waters is that known as the hot-water method; the volatile oil may either be dropped upon shredded filter paper, and this shaken with hot water in a strong bottle for some time, or the oil may be dropped into a stone jug and run around the sides, after which the hot water is added and agitated until cold; in either case the finished solution is passed through a paper filter, and will be found of excellent quality. The most important of the official waters is undoubtedly distilled water, because it is intended to be absolutely free from impurities, inorganic as well as organic, and is the only kind that should be used in making aromatic waters. River water and most spring waters contain in solution varying quantities of mineral compounds, and frequently carbon dioxide and organic matter, which render the water unfit for many pharmaceutical purposes; boiling and subsequent filtration through sand and charcoal will improve the water, but do not remove the salts held in solution, which if present in appreciable quantity will cause precipitation if silver nitrate or lead acetate be dissolved in the water. The so-called hardness of water may be due to the presence of calcium sulphate, and is then known as permanent hardness, or it may be due to calcium carbonate held in solution by an excess of carbon dioxide, which is always the case with spring water coming from limestone districts; boiling such water expels the excessive carbon dioxide, causing the lime-salt to be precipitated, whereby it is rendered soft. The directions of the Pharmacopoeia to reject the first 10 per cent. of the distillate and to collect only 80 per cent. for use, are for the purpose of getting rid of the gases and volatile compounds always present in water, and to avoid the decomposition-products from ammonia compounds and organic matter, with which the last portions of water in the still are apt to be contaminated. The condensed steam from boiler pipes is frequently sold as distilled water, but, unless collected with care, will often be found very unsatisfactory and not up to the requirements of the Pharmacopoeia. In the manufacture of distilled water all contact with iron and lead should be avoided, and either glass or pure tin apparatus used, especially for the condensation of the vapors. The occasional appearance of confervæ (microscopic plants) in distilled water is due to the presence of minute spores derived from the air, and may be prevented by keeping it in vessels so arranged that the air can enter only after having passed through a layer of cotton. Aromatic waters made with distilled water are subject to the same difficulties. The addition of alcohol, which has been recommended as a preservative measure, is inadmissible, because a small quantity would predispose the water to acetous fermentation (souring), as has been proven, and larger quantities might interfere therapeutically. The following classification of the official waters shows, at a glance, their strength and mode of preparation : OFFICIAL WATERS MADE BY AGITATING THE MEDICINAL INGREDIENT WITH COLD WATER. Official Name. Aqua Amygdala Amaræ Aqua Creosoti Aqua Hydrogenii Dioxidi Aqua Rosa Strength. 0.1 per cent. by volume of Oil of Bitter Almond 50 per cent. of stronger Orange Flower Water. Saturated. About 0.5 per cent. by volume of Chloroform. 1 per cent. by volume of Creosote. About 3 per cent. by weight of pure Hydrogen Dioxide, or 10 volumes of available Oxygen. 50 per cent. of stronger Rose Water. Bitter almond water is likely to contain variable proportions of hydrocyanic acid, as this acid is usually present in the commercial oil; it is a weak and very uncertain preparation. The German Pharmacopoeia directs that bitter almond water shall be made by distillation and shall contain 0.1 per cent. of absolute hydrocyanic acid; this corresponds in strength to the distilled cherry-laurel water of the British Pharmacopoeia. OFFICIAL WATERS MADE BY PASSING GASES THROUCH WATER. Official Name. Aqua Ammoniæ Strength. 10 per cent. by weight of gaseous Ammonia. Chlorine water is very prone to change; it should always be kept in well-filled bottles, in a cool, dark place, as air and light hasten deterioration. |