William Hyde Wollaston (1766-1828), English chemist and discoverer of palladium and rhodium. In 1800, having given up a medical practice, Wollaston earned a living from the sale of platinum and was able to devote his time to studying chemistry and optics. While working with crude platinum ore he discovered the elements palladium (1802) and rhodium (1804). He also pioneered powder metallurgy, the use of heat and pressure to convert powders into metal articles. Wollaston made a number of contributions to science including a reflecting goniometer (for measuring crystal angles) and an improved microscope.