Date context
1766–1844
Teaching, weather and scientific societies
Dalton worked as a teacher, kept weather records and joined Manchester’s Literary and Philosophical Society. He also investigated his own colour-vision differences. Regular measurement, discussion and access to experimental facilities helped connect meteorology with questions about gases and composition.
Mixed gases and partial pressures
He described the pressure of a gas mixture as the sum of partial pressures and sought explanations using different kinds of particles. This line of work directed attention toward composition and particle properties rather than only large-scale meteorological phenomena.
An atomic model for chemistry
Dalton proposed that elements consisted of characteristic atoms and compounds formed through their combination in simple ratios. His ideas developed around 1803 and were systematically presented in A New System of Chemical Philosophy, whose publication began in 1808.
Usefulness and correction
Inferring atomic weights from mass measurements required assumptions about how many atoms a compound contained. Some led to incorrect assignments, including a one-to-one formula for water. Later work on chemical formulas, isotopes and subatomic structure revised the model while retaining the usefulness of atomic explanations.