Joseph Louis Gay-Lussac
Soon after his appointment as at the École Polytechnique he began a lifelong friendship with Joseph Louis Gay-Lussac, and the two carried out many research projects together. Careful analysis led him to dispute some of Claude Louis Berthollet's theoretical views regarding the composition of the metallic oxides, and he also showed Berthollet's "zoonic acid" to be impure acetic acid (1802). In response, Berthollet invited him to become a member of the Society of Arcueil.