Until the mid-18th century, chemists had no understanding of the role of air in chemical changes. The Chemical Revolution was not merely conceptual, but also instrumental in that it involved the practical ability to manipulate, weigh, and measure gases using accurate balances, glass apparatus, and eudiometers. The chemist who transformed our views of elements, composition, and reorganized the way that chemists communicated was the French civil servant Antoine Lavoisier (1743–94). ‘Gases and atoms’ outlines Lavoisier’s work on chemistry nomenclature along with the key chemical discoveries by Joseph Black, Henry Cavendish, and Joseph Priestley. John Dalton’s atomic theory and the problem of ascertaining the molecular structure of water are also discussed.