"In this case also, though I did not give sufficient attention to
the circumstance at that time, the flame of the candle, besides
being larger, burned with more splendour and heat than in that
species of nitrous air; and a piece of red-hot wood sparkled in it,
exactly like paper dipped in a solution of nitre, and it consumed
very fast--an experiment which I had never thought of trying with
nitrous air." [7]

Priestley obtained the same sort of air from red lead, but, as he says
himself, he remained in ignorance of the properties of this new kind of
air for seven months, or until March 1775, when he found that the new
air behaved with "nitrous gas" in the same way as the dephlogisticated
part of common air does; [8] but that, instead of being diminished to
four-fifths, it almost completely vanished, and, therefore, showed
itself to be "between five and six times as good as the best common air
I have ever met with." [9] As this new air thus appeared to be
completely free from phlogiston, Priestley called it "dephlogisticated
air."

What was the nature of this air? Priestley found that the same kind of
air was to be obtained by moistening with the spirit of nitre (which he
terms nitrous acid) any kind of earth that is free from phlogiston, and
applying heat; and consequently he says: "There remained no doubt on my
mind but that the atmospherical air, or the thing that we breathe,
consists of the nitrous acid and earth, with so much phlogiston as is
necessary to its elasticity, and likewise so much more as is required
to bring it from its state of perfect purity to the mean condition in
which we find it." [10]

Priestley's view, in fact, is that atmospheric air is a kind of