(1782). MARAT (J.-P.). PHYSICAL RESEARCH ON ELECTRICITY... Paris, de l'imprimerie de Clousier, 1782, in-8° of 8-467 (misprinted 461)-[3] pages, half navy blue basane (later binding). FIRST EDITION. Marat describes more than 200 personal experiences with 5 copper-engraved plates. Also by the same author. -PHYSICAL RESEARCH ON FIRE. Paris, Claude-Antoine Jombert fils, 1780. In-8 of [4]-202-[2] pages, bradel cardboard (Pierson). More than 150 experiments made with the solar microscope illustrated with 7 folding plates. Circles, ex. untrimmed. Edges of plates a little soiled. TOGETHER 2 VOLUMES.