The aim of this book is to give an account of the principal radiochemical methods used in chemical analysis. It is assumed that the reader already has some background knowledge of radioactivity, available from several general textbooks. For this reason some subjects, e. g. the fundamentals of radio activity, the properties of radiation, statistics of counting procedures, the precautions needed in working with radioactive materials, which could have occupied half the text, are not considered in detail. The different aspects of radiochemical analysis have been covered by specialized books and reviews, e. g. on activation analysis, gamma spectrometry, radiometric titrations. A good deal of information is in the form of reports of meetings and symposia and liquid scintillation counting, for instance, has been mainly covered in this way. There are also a large number of journals. It is therefore hoped that this book will help fill the gap between the introductory texts and the specialized sources, many of which are referred to in the chapter references. The ftrst three chapters in the present volume deal with the methods of measurement of radioactive nuclides. Chapter I gives a general account of detection and measurement techniques. The next two chapters are devoted to two specialized techniques: gamma-ray spectrometry and liquid scintilla tion counting.