How did Joseph Black contribute to chemistry during the Scottish Enlightenment?

During the Scottish Enlightenment, Joseph Black made foundational contributions to chemistry by establishing that gases could be distinct chemical substances rather than merely atmospheric air in different states.1

His seminal research on alkalinity, detailed in his 1755 and 1756 papers, utilized quantitative experiments with a balance to identify "fixed air." By heating magnesium and calcium compounds, he demonstrated that the gas released was a specific component of the substance itself, not a product of the fire. This discovery of fixed air—now known as carbon dioxide—paved the way for the characterization of other gases, such as oxygen and hydrogen, by his contemporaries.1

Additionally, Black conducted pioneering work on heat phenomena. He distinguished between temperature and the quantity of heat, discovering latent heat through experiments on the melting of ice and the vaporization of water. His insights into latent heat were instrumental to his friend James Watt in the development of the steam engine.2