Assistant to Berthollet

Gay-Lussac was fortunate in having the resources of the Ecole Polytechnique on which to draw, but he was doubly fortunate in having a second source of support as a semi-permanent guest at Berthollet's country house at Arcueil, a few kilometres to the south of Paris. It was in the autumn of 1801 that Berthollet, General Bonaparte's former companion in Egypt and now a senator, decided to buy another property which he could equip as a centre of research. Complementing his good library there were practical facilities, excellent by the standards of the time, consisting of a chemistry laboratory and a physics laboratory, well endowed with apparatus. It was in this environment that Gay-Lussac was to work under the supervision of Berthollet.

The role of Berthollet in Gay-Lussac's life merits careful examination. It was without doubt the most important personal influence in the latter's whole life. Berthollet's role was in the first place that of a teacher. But in the case of Berthollet the term ‘teacher’ has a special meaning. Unlike his colleague, Fourcroy, Berthollet was a poor lecturer and the fact that a person attended his lectures is unlikely to have made any deep impact on him. Gay-Lussac was Berthollet's student in the more personal sense of being initially a research assistant.