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 proved 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 has been 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 waters, as well as those known as medicated waters; all the latter are solutions of volatile substances, and were it not for this pharmaceutical classification three 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 ammonic fortior, and aqua hydrogeni 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 purified tale 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.

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 likely to be contaminated.

The condensed steam from boiler pipes is sometimes 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 following classification of the official waters shows at a glance their strength and mode of preparation :

Bitter almond water is likely to contain variable proportions of hydrocyanic acid, as this 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 Pharmacopœia.

OFFICIAL WATERS MADE BY TRITURATING THE MEDICINAL INGREDIENTS WITH PURIFIED TALC, AND THEN MIXING WITH COLD DISTILLED WATER AND FILTERING.

With the exception of camphor water, this whole class is prepared by triturating the oil with about 8 times its weight of purified tale, after which the distilled water is gradually added with continued trituration; the mixture is finally filtered through paper. Thorough trituration with an insoluble powder causes division of the oils into minute particles, in which condition they are more readily dissolved by water. In the case of camphor water, 8 Gm. of camphor are dissolved in 8 Cc. of alcohol, and then triturated with 15 Gm. of purified tale until the alcohol has evaporated, after which the preparation is finished like the others. It is important that the purified tale be not used in the form of an impalpable powder, as this is apt to pass through the filter and necessitate frequent refiltration, but a coarser powder, about No. 60, should be employed. Permission is also given in the Pharmacopoeia to effect solution of the volatile oil by replacing the purified tale by pulped or shredded filterpaper, or by the addition of oils to hot water and separation of the excess of the former after active agitation and subsequent cooling of the mixture, or by distillation of the drug or oil with water. When shredded filter-paper is used, the best plan is to drop the oil upon the shredded paper, add this to the hot distilled water contained in a strong bottle or jug, and shake actively until the liquid is cold, after which a perfectly clear solution may be obtained by simple filtration. In the author's experience this method produces excellent results with little labor. The use of alcohol for the purpose of facilitating solution of the oil in the water must be condemned as liable to cause trouble, the very weak alcoholic liquid having a tendency to become sour through oxidation under favorable conditions. Calcium phosphate, directed in the U. S. P., 1890, is not a good medium for division of the oils, and is frequently found impure from contamination with soluble matter. Magnesium carbonate, at one time largely used, is not desirable, as it is not wholly insoluble, and this fact has often given rise to trouble, as in the case of cinnamon-water, which invari

ably has a yellow color when made with this agent, and in the case of mixtures of medicated waters with lime-water, producing turbidity.

Aqua Aurantii Florum Fortior. Stronger Orange Flower Water. Saturated.

Aqua Destillata

Aqua Hamamelidis .

Aqua Rose Fortior.

Distilled Water

Strength.

Absolutely pure.

(?) Saturated.

Aromatic waters made by distillation possess in many instances a more agreeable flavor than the aqueous solution of the corresponding volatile oils, which is probably due to the fact that, besides the volatile oil, other volatile compounds, such as acids or ethers, are present in the drug, and, passing over with the steam, remain dissolved in the condensed water. In distilling aromatic waters over a naked fire care should be taken to prevent the material from being scorched, which can be obviated by placing the drug either upon a diaphragm or in a perforated vessel or wire cage, and then suspending this in the water. A peculiar odor is observed in some waters immediately after they have been distilled and condensed in tin vessels, but not when glass vessels have been used; if the waters be exposed to the air in loosely stoppered vessels for a few days, this still-odor disappears and the natural odor of the water becomes apparent.

The stronger orange flower and rose waters are obtained, on a large scale, often as by-products in the distillation of the respective oils; in commerce they are distinguished as of triple or quadruple strength. In order to produce a saturated solution of the oil, recourse is had to the process of cohobation or redistillation, which consists in distilling the same water two or three times with fresh portions of the flowers. In some factories saturated orange flower and rose waters are obtained, not as by-products, but direct from the flowers, by distilling them with relatively small quantities of water; thus triple strength water is distilled by using 3 parts of the flowers to 1 of water, etc. According to Schimmel & Co., sextuple rose water represents the highest obtainable concentration, and rose water prepared from more than 6 times its weight of roses will not retain the whole of its oil in solution at ordinary temperature.

For the preparation of distilled water a special apparatus has been put upon the market, which is said, by those who have used it, to yield an exceptionally pure water and in considerably larger quantity than is usually expected from a still of like size. The apparatus, which is illustrated in Fig. 213, is known as the Curran water still, and can be used anywhere if gas and constant watersupply be available.