August 21st

Charles (-Frédéric) Gerhardt was born on this day in 1826. French chemist who, with Auguste Laurent, developed a classification of organic compounds. Like most chemists he was aware that the dualistic system of Jöns Berzelius was unsatisfactory and tried to create an alternative. He adopted what became known as type theory in which he thought all organic compounds were based on four main types – hydrogen, hydrogen chloride, ammonia, and water. Organic compounds were referred to these types by replacing a hydrogen atom in one of these compounds by a radical (i.e., by a group of atoms). His idea was opposed by his contemporaries and was later abandoned, but it proved important in the subsequent rationalization of structural organic chemistry.