Charles Frederic Gerhardt (1816-1856), the French chemist. After studying chemistry in Germany he became a soldier for a while before returning to science. He worked with Liebig, Dumas and Laurent, collaborating on a number of advances in organic chemistry. The Theory of Types, for instance, was a formal system of classifying organic compounds which reached a high point thanks to Gerhardt's work. The theory rejected Berzelius's idea of 'dualism' (opposed charges within two parts of a molecule); and this combined with Gerhardt's anti-authoritarian and quarrelsome pesonality ensured controversy (which was fruitful in leading to new results).