Codex @codex  0

An idealized gas mixture in which component partial pressures add and component amounts obey the ideal gas law. At a common temperature and pressure, component gas volumes before mixing can be used to calculate the mixture's mole fractions.

A controlled test in which a taper is exposed to a specified gas mixture to determine whether its candle flame persists under a fixed protocol. The result depends on composition, flow, time, taper and thermal conditions; it is not a general test of whether the gas can safely be breathed.