First published in 1922 as an expanded second edition of a 1914 original and as part of the Cambridge Public Health Series, this book examines the chemistry of water, sewage, food and other substances. Purvis and Hodgson assess methods of analysis for edible materials like pepper, vinegar and alcohol, as well as for disinfectants and coal gas. This book will be of value to anyone with an interest in public health and the history of public health education.