raneous preparations such hints are incorporated as are particularly applicable to the compounding of each article under consideration; and they may be prefaced by a few general suggestions which will serve to point out the most approved method of dealing with this important part of the druggist's work. The prescription should first be slowly read over in a critical spirit, but no word or action of unfavorable criticism should reach the ears or eyes of the messenger. To shrug the shoulders while scanning the items, to laugh or even smile at the phraseology, to question the person offering it as to whom it is for, or what complaint it is given for, are instances of such flagrant treason to the prescriber as would justify the most complete professional ostracism of the offender. The compounder has no business whatever with the propriety of the recipe for its purpose. It might have been given as a placebo for reasons eminently wise and judicious; or if not so constituted it has at least been ordered by one who is in possession of facts which the druggist knows nothing about, even if by education. and experience he were competent to judge in the matter, which he seldom is. His criticism should be directed only to the dosage and the pharmaceutical compatibility of the ingredients. Even in the latter case he must remember that incompatibles are often prescribed with the view of forming another agent from the chemical reaction produced. If he thinks that there is any mistake, and the drugs ordered are in any degree poisonous, it is his duty to make an excuse for delay to the messenger and at once communicate with the physician. This course, in these days of telephones, is nearly always practicable. After reading the prescription, it is well to number it and write the label. This gives time for the label to dry, and avoids the use of blotting paper, which often mars the writing and renders the directions all but illegible. A clearly defined method should next be decided on by which to compound the prescription. Directions for such plans of procedure will be found in the succeeding pages under the titles of the various preparations. Next, the ingredients should be carefully weighed or measured out, each one being checked off so as to avoid the danger of its being duplicated. In many cases the excipient is not specified, its choice being left to the druggist; but in all such a note should be made on the prescription to show the article used, in order that in the event of a renewal there may be no difference perceptible. No alteration or addition should ever be made which would in any degree affect the medicinal action of the prescription, or interfere with the obvious intention of the prescriber. The labelling of the package and the numbering and filing of the prescription are matters of mechanical detail which are best learned at the counter. Various devices for simplifying these operations are in vogue PRESCRIPTIONS. 455 and may be seen in any well-appointed drug-store. Poisonous articles. sold by the druggists should always be labelled "Poison," and the transaction entered in a book usually required by law to be kept for that purpose; but in the case of prescriptions the word "Poison" should not appear on the package or label unless so directed by the prescriber. Stock Solutions of the salts most frequently prescribed are kept in many establishments for convenience in dispensing. Those most generally used are the following: Alum,ijss in a quart of distilled water. Of this solution each fluidounce represents 3 ss of the salt. Potassium Bicarbonate,-3j in fiv of distilled water; of which 3 ss contains 3j of the salt. Potassium Chlorate,-I in 24 of distilled water, will not crystallize as the temperature changes. Potassium Bromide,-I in 3 of distilled water, makes a very convenient solution for dispensing purposes. Chloral Hydrate,-I in I of distilled water; of which each minim contains a grain of chloral. Morphine Sulphate,—gr. xvj in 3j of distilled water, with a grain of Salicylic acid or 3 drops of Carbolic Acid to prevent change. Of this solution, known as Magendie's, each minim contains gr. of the salt, and mx contain gr. 1. A safer solution is the Liquor Morphia Sulphatis of the U. S. P., 1870, which had one grain of the salt in each fluid ounce. Carbolic Acid,-3j in fiv of glycerin, makes a convenient solution which will mix with water in all proportions. mivss represent gr. j of the acid. Tannic Acid,-3) in fiv of glycerin, dissolved by the aid of a gentle heat. mivss represent gr. j of the acid. The following rules for the pharmaceutical student are quoted from the Chemist's and Druggist's Diary for 1885. They are well worth remembering. 1. Read through a prescription, rapidly and in a manner suggesting no suspicion or doubt. 2. Write directions invariably before dispensing. Avoid thus the use of blottingpaper; a good dispenser uses almost none. 3. If a mixture contains readily soluble ingredients, never use a mortar. 4. Avoid effecting solution by heat, for fear of recrystallization. 5. With syrups and also ingredients not water, arrange in dispensing to rinse out the measure and leave it clean; a skilled dispenser shows very little traces of his work.. 6. Carefully clean and put away weights and scales after each operation. 7. Hold the scales firmly by the left hand, never lift them high above the counter, and judge of the weight as much by the indicator as by the position of the scale. 8. Select glass pans for scales, preferably of heavy make, and discard flimsy brass material, which corrodes speedily and becomes inaccurate. 9. Learn to judge of the quantity to be weighed with tolerable accuracy; train the eye as well as the hand. 10. If in doubt, always begin with that about which you have no doubt. 11. Be rapid in manipulation. Finish wrapping, tying, or sealing quickly. Slow dispensing is bad dispensing, and arises either from deficient practice or want of knowledge. 12. Never, when in a shadow of doubt, hesitate to ask advice from a fear of compromising your own dignity. INCOMPATIBILITY. Incompatibility may be Chemical, Pharmaceutical or Therapeutical, according to the prescribed combination results in chemical decomposi tion, physical disassociation or antagonistic action. In the first case the incompatibility may be unintentional or intentional on the part of the prescriber, for in many cases the result of the chemical action affords the substance desired. Instances of intentional incompatibility are the mixtures of Calomel and Corrosive Sublimate with Limewater, producing the Black and Yellow Oxides of Mercury respectively, and commonly known as "Black Wash" and "Yellow Wash." Such combination should not be filtered (as a novice might suppose), but should be dispensed with a Shake-label," that the precipitate may be uniformly distributed before using. Chemical Incompatibility generally results from neglect on the part of the prescriber of the most common chemical reactions, such as— I. Acids tend to combine with bases and to form salts. 2. Weak acids or bases are displaced from their combinations by stronger ones, so that salts in solution when brought together generally exchange their radicles, especially if by doing so an insoluble compound can be formed. 3. A salt in solution is easily decomposed by a strong alkali if the salt is one having a weak or volatile base. 4. A substance in solution may be decomposed by another without precipitation, the product being soluble in the solution. 5. Alkaloidal salts are precipitated from their solutions by the addition of fixed alkalies, their salts or salts which produce insoluble compounds. Oxides of the fixed alkalies decompose salts of the metals proper, and those of the alkaloids, precipitating their bases; but the base may be soluble in an excess of the alkali. 6. Tannic or Gallic Acids and vegetable substances containing them. precipitate albumen, alkaloids and most of the metallic oxides, and form inky solutions when brought into contact with the persalts of Iron. Tannic Acid precipitates gelatin. 7. Glucosides are incompatible with free acids or Emulsin. Examples of the neglect of these principles are seen in the prescribing of Quinine Sulphate in mixture with Potassium Acetate, resulting in a voluminous precipitate of Quinine Acetate which could not be poured from the bottle;-Vinegars or Syrups containing Acetic Acid (Syr. Allii, Syr. Scilla) added to a solution of alkaline carbonates, causing decomposition of the latter with evolution of CO, ;-the addition of Liquor Potassæ to a solution of Ammonia-alum, setting free gaseous ammonia;-the mixing of Strychnine Sulphate and Potassium Bromide in solution, causing the decomposition of the alkaloid sulphate and precipitation of Strychnine;-preparations of Cinchona with salts of Iron, forming an inky tannate of Iron; Elixir of Chloral with alkalies, causing the elimination of Chloroform and its subsequent evaporation, etc., etc. The following table shows the most important instances of solutions INCOMPATIBILITY. which mutually precipitate each other, the letter P meaning "forms a 457 precipitate with" : The following more or less insoluble salts will be formed whenever the materials of which they are composed are brought together in solutions: the Hydrates, Carbonates, Phosphates, Borates, Arseniates and Tannates of most earthy and heavy metals and alkaloids, and the metallic Sulphides; the Sulphates of Calcium and of Lead, and the subsalts of Mercury; the Chlorides, Iodides, and Bromides of Bismuth, Silver, Lead, and subsalts of Mercury; the Iodides of Quinine, Morphine, and most alkaloids. Instances are-Limewater or Aromatic Spirit of Ammonia with Tincture of Chloride of Iron, or solutions of Mercury salts, or neutral solutions of Quinine or Morphine salts. Ammonium, Potassium, and Sodium carbonates or bi-carbonates with Limewater. Solutions of Magnesium Sulphate, Alum, Zinc Acetate, or Sulphate with solutions of salts of Iron, Manganese, Bismuth, Antimony, Lead, and of most alkaloids. Ammonium or Sodium Phosphates with solutions of Iron salts, with Limewater, solution of Magnesium Sulphate, of Alum, etc. Liquor Potassii Arsenitis with Lime water, with solutions of basic salts of Iron, and of neutral salts of Quinine and Morphine, etc. Solutions, Decoctions, Tinctures, and Extracts containing Tannic Acid with solutions of salts of Iron, Mercury, Antimony, Lead (as also with solutions containing albuminous substances and Gelatin). Limewater with solutions of Quinine and Morphine Sulphates. Solutions of Lead Acetate with Zinc Sulphate or Alum. Sodium Chloride with Silver Nitrate. Morphine Hydrochlorate with Lead Acetate. Alkaline Iodides or Bromides with Bismuth Carbonate or Sub-nitrate, with Lead Acetate, with Subchl-oride of Mercury, or with neutral solutions of Quinine, Morphine, and Strychnine salts. Explosive Compounds result from the admixture of powerful oxidizing agents with substances which are readily oxidizable. The most important members of these two classes are as follows: Oxidizers. Nitric Acid. Chromic Acid. Free Hydrochloric Acid. Nitro-hydrochloric Acid. Potassium Chlorate. Potassium Permanganate. Oxidizable or Combustible. Glycerin, Sugar, Alcohols. EXPLOSIONS have resulted from mixing Fluid Extract of Uva Ursi with certain samples of Spirit of Nitre, Chromic Acid with Glycerin, Permanganate of Potassium with Glycerin, Nitric Acid with Glycerin, Nitrate of Silver with Creasote, Oxide of Silver in pill with Extract of Gentian, Potassium Chlorate with Glycerin and Tincture of the Chloride of Iron. Chloride of Lime triturated with Sulphur in a mortar has exploded, so also has Calcium or Sodium Hypophosphite when triturated alone. Tincture of Iodine with Ammonia forms the Iodide of Nitrogen, which is highly explosive, especially if triturated in the presence of water. Catechu and Potassium Chlorate in a dentifrice have exploded in the mouth from the friction produced by a dry toɔth-brush. Poisonous Compounds may be formed by the admixture of many substances in solution, such as— Potassium Chlorate with Potassium Iodide, in solution together do not react at ordinary temperatures, but in the system they evolve a poisonous agent, probably the Iodate of Potassium. Potassium Chlorate with Syrup of Iodide of Iron, liberates Iodine from the Iodide in the warm stomach, causing severe gastric irritation, perhaps gastritis of dangerous degree. Dilute Hydrocyanic Acid or Potassium Cyanide, with Calomel, forms the Bichloride and Bicyanide of Mercury, both virulent poisons;—with metallic hydrates, carbonates, sub-nitrates, or sub-chlorides, cyanides of the metals are formed which are even more poisonous than the acid itself in its usual diluted form. Pharmaceutical Incompatibility differs from chemical incompatibility in the absence of chemical action, and is generally produced by adding one substance to another which, through differences in solubility, causes a precipitation of solid matter or a separation of part of the liquid. The constituents separated may be active and hence important, or inert and therefore unimportant. Instances of this are--the addition of an acid to a Quinine and Liquorice mixture, resulting in precipitation of the Glycyrrhizin (relied on to cover the taste of the Quinine) by the acid; or the use of Quinine, Tincture of Ferric Chloride and Liquorice together;-or the prescribing of solutions of Chloral and Potassium Bromide with an alcoholic preparation, the Chloral separating to the top as an alcoholate, and therefore dangerously in excess for the first few doses;-or the neglect to prescribe Acacia or some other emulsifier in mixtures of an alcoholic fluid extract of a resinous body with an aqueous preparation, which would result in the separation of the resin to the surface and an overdose with the first teaspoonful. When the fluid extracts are diluted with liquids differing in composition. from those used in the fluid extracts, the gum, albumen, resin, and mucilage are often separated. In such a case as Fluid Extract of Cannabis |