above a beer vat at a brewery and synthesizes carbonated water (1767). Antoine Lavoisier determines that oxygen combines with materials upon combustion, thus disproving phlogiston theory (1783). Antoine Lavoisier determines that chemical reactions in a closed container do not alter total mass. From these observations he establishes the law of conservation of mass (1789). Benjamin Thompson, Count Rumford demonstrates that the heat developed by the friction of boring cannon is nearly inexhaustible. This result was presented in opposition to caloric theory (1798). Humphry Davy uses electrolysis to isolate elemental potassium, sodium, calcium, strontium, barium, magnesium, and chlorine (1807–1810). Joseph Louis Gay-Lussac studies reactions among gases and determines that their volumes combine chemically in simple integer ratios (1809). Robert Brown studies very small particles in water under the microscope and observes Brownian motion which was later named in his honor (1827). Friedrich Wöhler synthesizes the organic compound urea using inorganic reactants, disproving the application of vitalism to chemical processes (1828). Thomas Graham measures the rates of effusion for different gases and establishes Graham's law of effusion and diffusion (1833). Julius Robert von Mayer and James Prescott Joule measure the heat generated by mechanical work. This establishes the principle of conservation of energy and the kinetic theory of heat (1842–1843). Louis Pasteur separates a racemic mixture of two enantiomers by sorting individual crystals, and demonstrates their impact on the polarization of light (1849). Anders Jonas Ångström observes the presence of hydrogen and other elements in the spectrum of the sun (1862). François-Marie Raoult demonstrates that the decrease in the vapor pressure and freezing point of liquids caused by the addition of solutes is proportional to the number of solute molecules present. This establishes the concept of colligative properties (1878). Svante Arrhenius studies the conductivity of salt solutions and determines that salts dissociate into ions in water (1884). Svante Arrhenius determines the impact of temperature on reaction rates and formulates the concept of activation energy (1889). William Ramsay and Lord Rayleigh (John Strutt) isolate the noble gases (1894–1898). Henri Becquerel, Marie Curie, and Pierre Curie discover radioactivity and describe its properties (1896). Mikhail Tsvet (Mikhail Semyonovich Tsvet) separates chlorophyll from other plant pigments using chromatography (1901). Frederick Soddy and William Ramsay observe the production of helium from alpha particles during radioactive decay (1903). Ernest Rutherford discovers that atoms have a very small positively charged nucleus in the gold-foil experiment, also known as the