Jons Jacob Berzelius, Swedish chemist, c 1843.
© Science Museum / Science & Society Picture Library
Later engraving by CW Sharpe after an 1843 painting by Olof Johan Soedermark of Berzelius (1779-1848). Berzelius devised the first consistently accurate method of using the oxidation technique developed by Joseph Louis Gay-Lusac (1778-1850) and Louis Jacques Thenard (1777-1857); a technique which allowed surveys of organic composition to be made. His accurate determination of atomic weights established the laws of combination and John Dalton's (1766-1844) atomic theory. He introduced modern chemical symbols and discovered the elements selenium, thorium and cerium.