Scottish chemist generally credited with dissevering nitrogen (1772). Joseph Black assigned him the task of investigating air incapable of supporting combustion. After carefully isolating and processing such air to remove carbon dioxide, Rutherford believed he had phlogisticated air—air having absorbed as much phlogiston as possible. According to phlogiston theory, respiration and combustion require the release of phlogiston, thus phlogisticated air could not support such processes. Antoine Lavoisier later described the true nature of nitrogen.