Jons Jacob Berzelius (1779-1848), Swedish chemist. After studying medicine, Berzelius specialised in chemistry and began a systematic survey of elementary proportions in a variety of compounds, which helped to confirm Proust's law. He went on to produce the first accurate table of atomic weights of the elements. He also introduced initial letter symbols with subscripts to describe compounds (thus ammonia would be NH3), and established himself as the world's leading authority on chemical theory. Berzelius discovered the elements selenium, cerium and thorium. He was made a baron on his wedding day by the King of Sweden.