A great English chemist, born at Penzance; conceived early in life a passion for the science in which he made so many discoveries; made experiments on gases and the respiration of them, particularly nitrous oxide and carbonic acid; discovered the function of plants in decomposing the latter in the atmosphere, and the metallic bases of alkalies and earths; proved chlorine to be a simple substance and its affinity with iodine, which he discovered; invented the safety-lamp, his best-known achievement; he held appointments and lectured in connexion with all these discoveries and their applications, and received knighthood and numerous other honours for his services; died at Geneva (1778-1829).