The purpose of this book is to provide the reader with a series of work ed examples in X -ray spectrometry and X -ray diffractometry, in such a way that each example can be treated either as a posed question, i. e. one to which the reader must himself provide an answer, or as a guide to the method of treating a similar problem. The latter, of course, also pro vides a check on the answer produced by the reader. Although much basic theory can be derived by study of this work the first intention of the book is not to provide a source of basic theoretical knowledge in X -ray analy sis. It is hoped that the book will be utilized more as a guide line in the tackling of theoretical and practical problems and as a means of estab lishing whether or not the reader is able to work out for himself a certain type of problem. For example, the series of examples on counting statis tics has been chosen in such a way that after working through and under standing these, the reader should be able to handle most of the calculations that he is likely to come up against in this area.