William Wollaston (1766-1828), English chemist. Wollaston is known for his discovery of palladium and rhodium. In 1800, having given up a medical practice, Wollaston earned a living from selling platinum. While experimenting with platinum ore, he discovered the elements palladium (1802) and rhodium (1804). He also pioneered powder metallurgy, where metal powder is molded into solid pieces using heat and pressure, and invented the reflecting goniometer for measuring crystal angles.