Statements of composition refer in some cases to percentage by volume, in others to percentage by weight, and in still others to percentage by weight-volume--that is, the weight of a given chemical contained (or the weight of a given vegetable drug represented by extractives) in 100 Cc. of the preparation. It has not been thought worth while to indicate whether the statement in each case is by volume, weight or weight-volume, since the differences are too small to have any therapeutic importance. Statements of alcoholic content refer to percentage by volume and are approximate only. In a few instances in which the quantity of alcohol in a dose is small, or in which the preparation is intended for external use, the alcohol content is not stated. DOSAGE statements, when followed by the letters "U.S.P." or "N.F.," are taken from these books, respectively, and are understood to be the average adult doses. In some cases in which this statement was felt to be inadequate or unsatisfactory, further suggestions as to dosage have been added. PREFACE TO SECOND EDITION The text of this edition is the same as that of the first, except that a few typographical errors which were in the first edition have been corrected. The new edition differs from the first in the following particulars: In the first edition, a star indicates that the drug is included in the second (1916) edition of Useful Drugs. To bring the present edition up to date, the star (*) here indicates that the drug is included in the fifth (1921) edition of Useful Drugs. In compliance with the opinion expressed by some that a more complete index would be helpful, the index to the second edition has been materially extended. It is hoped that this will help to familiarize those who purchase the book with its contents. TABLES OF METRIC AND APOTHECARIES' WEIGHTS AND MEASURES METRIC MEASURES OF WEIGHT 1 Milligram (1 mg.) = 0.001 gram. 1 Centigram = 0.01 gram. 1 Decigram = 0.1 gram. 1 Gram (1 Gm.) = 1.[A] 1 Decagram = 10 grams. 1 Hektogram = 100 grams. 1 Kilogram (1 kg.) = 1000 grams.[B] A: The weight of 1 cubic centimeter of water at 4 C. B: The weight of 1 cubic decimeter of water at 4 C. METRIC FLUID MEASURE 1 Milliliter (1 cubic centimeter, 1 Cc.) = 0.001 cubic decimeter. 1 Centiliter (10 Cc.) = 0.01 cubic decimeter. 1 Deciliter (100 Cc.) = 0.1 cubic decimeter. 1 Liter (1000 Cc.) = 1 cubic decimeter. APOTHECARIES' WEIGHT 20 Grains = 1 scruple. 3 Scruples = 1 drachm. 8 Drachms = 1 ounce. 12 Ounces = 1 pound. APOTHECARIES' FLUID MEASURE 60 Minims = 1 fluidrachm. 8 Fluidrachms = 1 fluidounce. 16 Fluidounces = 1 pint. EQUIVALENTS OF APOTHECARIES' WEIGHT IN METRIC 1 Grain = 0.06479895 Gm. 1 Drachm = 3.8879369 Gm. 1 Ounce = 31.1034956 Gm. 1 Pound = 373.241948 Gm. EQUIVALENTS OF APOTHECARIES' FLUID MEASURE IN METRIC 1 Minim = 0.06161 Cc. 1 Fluidrachm = 3.6966 Cc. 1 Fluidounce = 29.573 Cc. 1 Pint = 473.17 Cc.