French chemist Claude Louis Berthollet (1748-1822) aided Antoine Lavoisier (1743-1794) in his research into gunpowder and in devising the modern method of naming chemical compounds. Lavoisier is considered to be the founder of the modern science of chemistry. His major work, the 'Traite elementaire de Chimie' (1789), contained many of the ideas that set chemistry on its modern path. He was also a member of the commision which devised the metric system.
© Science Museum / Science & Society Picture Library