In the preparation of this new edition Dr atherden has kept in mind the original character of the book as a textbook for those studying for degree or diploma examination in pharmaceutical Chemistry in great Britain, the Commonwealth and in America, with a wider application to practicing pharmacists and chemists. Part 1 gives a general account, in relation mainly to the British pharmacopoeia (B.Br.), of certain physical and Chemical method used in determining the purity of pharmaceutical substances, where the procedure in the United States pharmacopeia (U.S.Br.) differs notably in principle, a description of the method is given. Part 2 deals mainly with Inorganic Compounds in common use in pharmacy, and for convenience the simpler Organic Salts are also included. A brief summary of the General Chemistry of each element is followed by a description of those of its Compounds that are defined in monographs of the B.Br., or of the U.S.Br. Part 3 is a modernized treatment of Organic Chemistry (including electronic theory) with special reference to Compounds of pharmaceutical importance; a description of the pharmacopoeial standards of Official substances is placed at the end of the chapters in which they naturally fall. The scope and usefulness of this edition has been broadened by the inclusion of those substances of the U.S.Br. Which are not included in the B.Br.; And in order to keep this edition as up to date as possible mention has been made of some important drugs, not at present official but which are likely to appear in future pharmacopeias.