In
1876, having been elected senator for the Aisne, he was again entrusted by Prime Minister
Dufaure with the Ministry of Public Instruction. Because he was a
Protestant, he was not permitted to combine the Ministry of Public Worship with the Public Instruction portfolio, as had been the custom in ministerial assignments. His most important project, a bill transferring the granting of degrees to the state, was passed by the Chamber, but thrown out by the
Senate.
He continued to hold office under
Jules Simon, with whom he was overthrown on the famous
seize mai (
16 May, 1877). The triumph of the republicans at the general election brought him back to power the following December as
Minister of Foreign Affairs, again under Dufaure. He was one of the French plenipotentiaries at the
Berlin Congress. The cession of
Cyprus to the
United Kingdom was, at first, denounced by the French newspapers as a great blow to his diplomatic reputation, but he obtained, in a conversation with
Lord Salisbury, a promise that the United Kingdom would, in return, allow France a free hand in
Tunis.