Rochelle Salt

Rochelle Salt, also known as potassium sodium tartrate, is a crystalline compound historically used in medicine, food, and science. Chemically, it’s a double salt formed from tartaric acid and potassium and sodium ions. It’s notable for its piezoelectric properties—meaning it can generate an electric charge when subjected to mechanical stress—and was used in early electrophysiological experiments. In pharmaceuticals, Rochelle Salt acts as a laxative and a mild electrolyte. Its unique electro-mechanical properties also made it valuable in the development of sensitive scientific instruments, although its practical uses have declined with more modern materials.