The thermal springs of Rapolano, known since antiquity, as demonstrated by the recent discovery of a thermal complex from Roman times at Campo Muri, were analysed by many chemists and naturalists, especially under the government of the Lorraines. Among these we may recall Francesco Hoefer, Giorgio Santi and later, Antonio Targioni Tozzetti. The progress achieved by chemistry by the middle of the 18th century was to prove essential for the scientific study of thermal waters, which was conducted with the support of new theories, new methods and new instruments. Studying these waters consisted of determining the physical characteristics of the water at the spring, and evaluating its heat, odour and taste. It also consisted of chemical analysis, conducted with particular reagents to determine the water's composition and, lastly, determination of the therapeutical effects based on which each kind of water could be prescribed for specific illnesses. Still today the Baths of Rapolano attract a great number of visitors, thanks to the beneficial effects of its sulphureous-bicarbonate-calcic waters and the beauty of the surrounding countryside.