Gay-Lussac's law gases and the gaseous products can be expressed in simple whole numbers. For example, Gay-Lussac found that 2 volumes of hydrogen and 1 volume of oxygen would react to form 2 volumes of gaseous water. Based on Gay-Lussac's results, Amedeo Avogadro theorized that, at the same temperature and pressure, equal volumes of gas contain equal numbers of molecules (Avogadro's law). This hypothesis meant that the previously stated result could also be expressed as The law of combining gases was made public by Joseph Louis Gay-Lussac in 1808. Avogadro's hypothesis, however, was not initially accepted by chemists until the Italian chemist
Potential temperature 1st law simplifies to: For approximately ideal gases, such as the dry air in the Earth's atmosphere, the equation of state, formula_18 can be substituted into the 1st law yielding, after some rearrangement: where the formula_20 was used and both terms were divided by the product formula_21 Integrating yields: and solving for formula_23, the temperature a parcel would acquire if moved adiabatically to the pressure level formula_24, you get: The potential virtual temperature formula_26, defined by is the theoretical potential temperature of the dry air which would have the same density as the humid air at a standard pressure P.