Dr. Priestley discovered that nitrous air or gas which he obtained by
dissolving metals in nitrous acid, would combine rapidly with vital air,
and produce with it a true nitrous acid; forming red clouds during the
combination; the two airs occupy only the space before occupied by one
of them, and at the same time heat is given out from the new
combination. This dimunition of the bulk of a mixture of nitrous gas and
vital air, Dr. Priestley ingeniously used as a test of the purity of the
latter; a discovery of the greatest importance in the analysis of airs.

Mr. Cavendish has since demonstrated that two parts of vital air or
oxygene, and one part of phlogistic air or azote, being long exposed to
electric shocks, unite, and produce nitrous acid. Philos. Trans. Vols.
LXXV. and LXXVIII.

Azote is one of the most abundant elements in nature, and combined with
calorique or heat, it forms azotic gas or phlogistic air, and composes
two thirds of the atmosphere; and is one of the principal component
parts of animal bodies, and when united to vital air or oxygene produces
the nitrous acid. Mr. Lavoisier found that 211/2 parts by weight of
azote, and 431/2 parts of oxygene produced 64 parts of nitrous gas, and
by the further addition of 36 parts of oxygene nitrous acid was
produced. Traite de Chimie. When two airs become united so as to produce
an unelastic liquid much calorique or heat is of necessity expelled from
the new combination, though perhaps nitrous acid and oxygenated marine
acid admit more heat into their combinations than other acids.]


"So Beauty's GODDESS, warm with new desire,
Left, on her silver wheels, the GOD of Fire;