Book excerpt: Eudiometers were instruments originally devised for checking the ‘goodness’ of common air. Seeking to be more than just a chronological inventory of eudiometers, this book presents a unique retrospective of these fascinating apparatuses from the end of the eighteenth century to the mid-nineteenth century. By paying particular attention to the experimental procedures involved over the course of the test, this book aims to understand and explore how eudiometers function, to describe the materials used in making them and the different reagents employed in each eudiometrical test. Importantly, eudiometers were employed within a variety of spheres including human and animal health, gas analysis, chemical theory, plant and animal physiology, atmospheric composition, chemical compound composition, gas lighting, chemical revolution and experimental demonstration. Finally, this book looks to redress the existing imbalance in the history of chemistry regarding the attention given to theoretical aspects of chemistry in comparison to chemical practice and apparatus. The few existing accounts of chemical devices written in the past century have not been sufficiently helpful for the understanding of experimental practice in chemistry. Until now no work that deals exclusively with eudiometers and gas analysis from a historical standpoint has been published. Thus, this book will not only cast new light on the subject, but will also contribute to further research on the history of chemical instruments.