Russian diplomat. Ambassador to France (1763-1773). While in Paris, he befriended many of the philosophes, including Helvétius and Voltaire. Named ambassador to The Hague (1773). An experimental scientist and one of the leading Russian intellectuals of his day. Published an edition of the Oeuvres of Helvétius (The Hague, 1773). Author of Description de la Tauride (1788), Description des minéraux (1792), and l’Esprit des Economistes (1796). Retired to Germany during the French Revolution.