Claude-Louis Berthollet

Born in 1748 in Talloires, in what is now France, Claude-Louis Berthollet trained as a physician before turning to chemistry. He became closely associated with Antoine Lavoisier and was part of the group that introduced a clearer chemical naming system in the late 18th century, helping make the subject easier to study and discuss.

Berthollet is especially remembered for his work on bleaching with chlorine and for his ideas about chemical affinity and reversible reactions. His book Essai de statique chimique (1803) was an important step toward physical chemistry because it treated chemical reactions as processes governed by general laws rather than fixed recipes.

He was also active in public life during and after the French Revolution, serving in scientific and governmental roles and later working in the learned circle at Arcueil. Although some of his theories sparked debate, his influence on modern chemistry was lasting, and he is still regarded as one of the major chemists of his era.