i regards its physical condition. In chemical solution more or less. alteration occurs in the properties of both the solvent and the substance dissolved. The percentage strength of solutions is either chemical or pharmaceutical. The chemical considers only weight and not volume; e.g., 10 gm. of a substance added to 90 gm. of a solvent, both being weighed, makes a 10 per cent. solution. The pharmaceutical is based upon the fact that solids are weighed and liquids measured so that if 10 gm. of a weighed substance are dissolved in a liquid menstruum and sufficient menstruum is added to make it measure 100 mils, the strength of the solution is 10 per cent. Standardizing consists in determining an upper or lower limit, or both, of the active constituent which a drug or its preparation must contain in order to be official, and prescribing an appropriate process for its determination. Where chemical methods have been proved to be inadequate, biological assays have been adopted. These are obligatory for Liquor Hypophysis and Cannabis and its preparations, and specified for Aconitum, Digitalis, Strophanthus, Scilla, Suprarenalum Siccum and their preparations. The standards adopted will be found in the descriptions of drugs and prepa rations. Sublimation is the process of separating a volatile solid substance, from one which is not volatile, by the application of heat. The product is termed a sublimate. The objects of sublimation are: (1) to purify volatile solids from admixed and fixed impurities, and (2) to provide a convenient means of collecting volatile solids resulting from chemical reaction at high temperatures. Trituration is the reduction of substances to fine particles by continued attrition in a mortar. When the substance is rubbed with sugar of milk, which is an inert and gritty powder, the product is designated a trituration. Usually 3 and 3 are written f13 and 13 when they stand for fluid drachms and fluid ounces. A pharmaceutical 1 per cent. solution is approximately a grain in 110 minims. A fluid grain is the volume of one grain of water at 15.5°C.; 60°F., that is to say, it is a little over a minim (1.05 M). In the pharmacopoeial description of the various proportions which several parts of a compound bear to one another, the word parts means parts by weight, the term fluid parts signifies the volume of an equal number of parts of water. Metrical System.—This, which is as follows, is official in the U. S. P. for the making of drugs and preparations. The United States Bureau of Standards having declared that the term cubic centimetre is a misnomer because there is a slight difference between the thousandth part of a litre and the cubic centimetre, (1 litre being equivalent to 1.000027 cubic decimetres), millilitre (abbreviation, mil) is substituted therefor. WEIGHTS I milligramme = 0.001 gramme. I decigramme = 0.1 gramme. I gramme (abbreviation, gm.) = weight of 1 mil of distilled water at 4°C.; 39.2°F. I dekagramme = 10.0 grammes. 1 hektogramme = 100.0 grammes. I kilogramme (abbreviation, kilo.) = 1000.0 grammes. In prescribing on the Continent of Europe all liquids are weighed and the weight used for both liquids and solids is grammes, but this word is not expressed. Thus A TEA-SPOONFUL is about a fluid drachm (4 mils). Usually it is more, viz., nearly 5 mils. A DESSERT-SPOONFUL is about two fluid drachms (8 mils). A TABLE-SPOONFUL is about half a fluid ounce (16 mils). Usually it is about 20 mils. A WINE-GLASSFUL is about one and a half to two fluid ounces (45 to 60 mils). A TEA-CUPFUL is about five fluid ounces (150 mils). A BREAKFAST-CUPFUL is about eight fluid ounces (240 mils). A DROP is often taken as being a minim, but drops vary so much in size that they should never be used for children, nor as a measure of powerful drugs. For example, the number of drops in a fluid drachm of the official Syrup of Acacia is 44, of Water 60, of Alcohol 146, of Chloroform 250. Spoons, glasses and cups vary so much in capacity that it is never safe to prescribe solutions of powerful drugs to be measured by them. The use of glass graduates, which can be obtained accurately marked, should be insisted upon. PHARMACOPŒIAL PREPARATIONS AND THEIR DOSES Most drugs are not, in their natural state, suitable for administration. They are either too bulky, too nauseous, or contain noxious principles. Preparations suitable for administration are, therefore, prepared from them according to "official" pharmacopoeial directions. The doses of the various official drugs and their preparations which may safely be administered are those given in the last revision of the United States Pharmacopoeia. These doses are intended to be "the average approximate (but neither a minimum nor a maximum) dose for adults." But these often may not be rigorously adhered to in prescribing, because they vary with the purpose for which the drug is required and the age of the patient. The following is an account of the preparation of the official remedies, with the doses so arranged that they may be readily memorized. Unless otherwise specified, the preparations are for internal use. Aceta (Vinegars).—Liquid preparations resulting from the extraction of the drug with dilute acetic acid, and filtering. The U. S. P. contains: Aquæ Aromaticæ (Aromatic Waters).-Preparations made by impregnating water with a volatile substance. Aromatic waters, when prepared from volatile oils, are intended to be, as nearly as practicable, saturated solutions, which must be clear and free from solid impurities, and unless otherwise directed, should be made by the following general process: Volatile oil, 2; purified talc, 15; distilled water, recently boiled, 1000. Triturate the volatile oil with the purified talc, add the distilled water gradually with continued trituration, filter and pass the filtrate through the filter repeatedly until the Aromatic Water is perfectly clear. Those in the U. S. P. thus made are: Aqua Ammonia Fortior. Dose Dose indeterminate. Dose indeterminate. Aqua Ammoniæ......I mil (15 M). Cerata (Cerates).—Adhesive preparations for external use, containing wax, capable of being spread at ordinary temperatures, and not melting at the temperature of the body. Three are official in the U. S. P.: Ceratum Ceratum Canthoridis. Ceratum Resinæ. Collodia (Collodions).-Preparations for external use, either simple collodion (a solution of pyroxylin in ether and alcohol) or collodion impregnated with an active substance. When applied externally a protective film is formed, owing to the rapid volatilization of the solvent. The U. S. P. contains three: Collodium. Collodium Cantharidatum. Collodium Flexile. Decocta (Decoctions).-Liquid preparations of organic drugs. Decoctions must be freshly made from the drugs, and when the strength is not otherwise directed they are to be prepared by the following general process: The drug, 50; water to 1000. Introduce it into a suitable vessel provided with a cover, pour upon it the water, cover it well, and boil for fifteen minutes. Then allow it to cool to about 40°C. (104°F.), express, strain the expressed liquid, and pass enough cold water through the strainer to make the product measure 1000. The strength of decoctions of energetic or powerful substances should be specially directed by the physician. The U. S. P. at present contains none. Elixira (Elixirs).—Sweet and aromatic liquid preparations, used for flavoring medicines. There are two in the U. S. P.: Elixir Aromaticum... Dose indeterminate. Emplastra (Plasters).-Tenacious preparations for external application, solid at ordinary temperatures, but pliable and adhesive at the temperature of the body. Those of the U. S. P. are: |