The use of modelling techniques in the analysis and solution of problems in science and other fields of knowledge is widespread and has often come under intensive scrutiny. This 1978 book concerns the use of models in learning, understanding, and practising chemistry. It will therefore be of interest to chemists, biochemists and chemical engineers in research and industry, and to many students of chemical science. The chemist uses models in his work not only in the material sense, for example molecular models, but also in his patterns of thought, coming to grips with chemistry and its applications through the manipulation of models. The present work outlines the scope of modelling and, from a discussion of the general principles involved, develops themes relevant to both academic and industrial scientists.