Robert Angus Smith (1817-1884) was a Scottish chemist and a leading investigator into what came to be known as 'acid rain'. This study of his life and work sheds light on the evolving understanding of sanitary science during the 19th century and of the need for regulation and enforcement of the chemical industries. It offers a fascinating insight into the changing landscape of British politics and is essential reading for historians of science, technology and industry in the nineteenth-century, as well as environmental historians seeking background context to the twentieth-century environmental movements.