Zionist leader, the first president of Israel (1948-52), and a chemist. He conducted the negotiations leading up to the Balfour Declaration, by which Britain declared its support for an independent Jewish state.

Born in Russia, he became a naturalized British subject, and as director of the Admiralty laboratories 1916-19 discovered a process for manufacturing acetone, a solvent. He became head of the Hebrew University in Jerusalem, then in 1948 became the first president of Israel.