Before revision: The thermal reaction may occur under a variety of atmospheres including: ambient air, vacuum, inert gas, oxidizing /reducing gases, corrosive gases, carburizing gases, vapours of liquids or "self-generated atmosphere"; as well as a variety of pressures including: a high vacuum, high pressure, constant pressure, or a controlled pressure.
After revision: The thermal reaction may occur under a variety of atmospheres including: ambient air, vacuum, inert gas, oxidising /reducing gases, corrosive gases, carburising gases, vapours of liquids or "self-generated atmosphere"; as well as a variety of pressures including: a high vacuum, high pressure, constant pressure, or a controlled pressure.