By factitious air, I mean in general any kind of air which is contained any in other bodies in an unelastic state, and is produced from thence by art. - Henry Cavendish

By fixed air, I mean that particular species of factitious air, which is separated from alcaline substances by solution in s or by calcination and to which Dr. Black has given that name in his treatise on quicklime.

Young people must break machines to learn how to use them; get another made!

I think we must allow that dephlogisticated air is in reality nothing but dephlogisticated water, or water deprived of its phlogiston; or, in other words, that water consists of dephlogisticated air united to phlogiston; and that inflammable air is either pure phlogiston, as Dr. Priestley and Mr. Kirwan suppose [and as Cavendish formerly supposed], or else water united to phlogiston; since, according to this supposition, these two substances united together form pure water. On the other hand, if the first explanation be true, we must suppose that dephlogisticated air consists of water united to a little and deprived of its phlogiston; but still the nitrous acid in it must make only a very small part of the whole, as it is found, that the phlogisticated air, which it is converted into, is very small in comparison of the dephlogisticated air.