Since then, there has been a succession of owners and doctors and the thermal baths have experienced a turbulent history, from discoveries to innovations, twists of fate and rebirth. The spa created by Gontard was an instant success. People flocked to the thermal baths of Saint-Gervais to benefit from its miraculous waters. In 1815, Doctor Mattey was appointed as the medical inspector. He catalogued the illnesses treated by the water and codified its uses: as a drink, baths, showers and later on, steam baths. He was in fact the first to scientifically prove its effect on skin diseases. As a result of these discoveries, the baths of Saint-Gervais continued to grow over the following decades. High society flocked to the thermal baths, they wer put up in the brand new hotels.
When Gontard handed over the thermal baths in 1838, the facility was thriving.