XXIVth International Congress of Pure and Applied Chemistry, Volume 4 contains lectures presented at the XXIVth International Congress of Pure and Applied Chemistry held at Hamburg, Federal Republic of Germany in September 1973. The book consists of papers discussing a wide range of subjects on pure and applied chemistry. The compendium has papers that deal with developments in the chemistry of the boron and silicon subhalides, chemical properties of the Si-H bond, and reactivity of phosphorus heterocycles. The text also presents papers covering topics on the effects of sulfur groups on acidities of carbon acids, aspects of the structural chemistry of polythionates, and Halogen cations. The book will be of use to chemists.