After giving a short sketch of the life of Dalton, the lecturer described the views that were held before his time with regard to chemistry, dwelling at some length on the “phlogistic” theory of Stahl. This was generally accepted by chemists for many years. The discoveries of Priestley and Cavendish, however, gave it a severe shock, and it was finally overturned by Lavoisier, who founded what may be called the new chemistry. Dalton threw himself eagerly into the path pointed out by Lavoisier, with the result of discovering what was the atomic theory, upon which the whole of modern chemistry was built. Dalton's theory was then described in detail, and it was pointed out how far it had been amplified by later observers. The general tendency of recent scientific thought in regard to atoms and the forces controlling them was also briefly alluded to.