Primarily used in the textile industry as a mordant to help dyes adhere to fabrics, enhancing color fastness and vibrancy. It is also employed in the production of certain types of glass and ceramics to improve clarity and durability. In medicine, it has been historically used as an emetic to induce vomiting and for treating parasitic infections such as schistosomiasis, though its use has declined due to safety concerns. Additionally, it serves as a reagent in analytical chemistry for detecting and quantifying specific substances in laboratory settings.