Jean-Baptiste Soleil’s main success story, remarkable both for its optical design and the mechanical construction of its quartz wedge compensator, is an instrument that can measure the rotational power of a solution and deduce its dissolved sugar concentration. In 1848, a report on it was submitted to the Academy of Sciences. It was used to determine the sugar based on a true assessment, and no longer only on the visual examination of products, before being deployed in the treatment of diabetes.