This chapter introduces the beginnings of chemistry—initially the discovery and characterization of the gases of air—oxygen nitrogen and carbon dioxide and not coincidently—two are the gases of respiration. The individuals, especially Antoine Lavoisier, but including Galileo, Torricelli, Robert hook Robert Boyle, John Mayow, and Richard Lower Identified, weighed, and showed the properties of these gases. Not only are their lives portrayed but their experimental methods are outlined in some detail.