Sir Cyril Norman HinshelwoodBorn 19 Jun 1897; died 9 Oct 1967 at age 70. English physical chemist who worked on reaction rates and reaction mechanisms, particularly that of the combination of hydrogen and oxygen to form water, one of the most fundamental combining reactions in chemistry. For this work he shared the 1956 Nobel Prize for Chemistry with Soviet scientist Nikolay Semyonov. Other important chain reactions are the combustion of carbon monoxide and of hydrocarbons. When it seemed that almost all reactions were chain reactions, one might believe the simpler mechanisms previously thought of were exceptions. But Hinshelwood found substances which could simultaneously react in two ways, one part reacting by a chain mechanism and at the same time the rest reacting in the old-fashioned way.