or rather light-blue flame, such as is seen when common salt is
thrown into the fire.

When this air is all expelled from any quantity of spirit of salt, which
is easily perceived by the subsequent vapour being condensed by cold,
the remainder is a very weak acid, barely capable of dissolving iron.

Being now in the possession of a new subject of experiments, viz. an
elastic acid vapour, in the form of a permanent air, easily procured,
and effectually confined by glass and quicksilver, with which it did not
seem to have any affinity; I immediately began to introduce a variety of
substances to it; in order to ascertain its peculiar properties and
affinities, and also the properties of those other bodies with respect
to it.

Beginning with _water_, which, from preceding observations, I knew would
imbibe it, and become impregnated with it; I found that 2-1/2 grains of
rain-water absorbed three ounce measures of this air, after which it was
increased one third in its bulk, and weighed twice as much as before; so
that this concentrated vapour seems to be twice as heavy as rain-water:
Water impregnated with it makes the strongest spirit of salt that I have
seen, dissolving iron with the most rapidity. Consequently, two thirds
of the best spirit of salt is nothing more than mere phlegm or water.

Iron filings, being admitted to this air, were dissolved by it pretty
fast, half of the air disappearing, and the other half becoming
inflammable air, not absorbed by water. Putting chalk to it, fixed air
was produced.

I had not introduced many substances to this air, before I discovered
that it had an affinity with _phlogiston_, so that it would deprive
other substances of it, and form with it such an union as constitutes
inflammable air; which seems to shew, that inflammable air universally
consists of the union of some acid vapour with phlogiston.

Inflammable air was produced, when to this acid air I put spirit of
wine, oil of olives, oil of turpentine, charcoal, phosphorus, bees-wax,
and even sulphur. This last observation, I own, surprized me; for, the
marine acid being reckoned the weakest of the three mineral acids, I did
not think that it had been capable of dislodging the oil of vitriol from
this substance; but I found that it had the very same effect both upon
alum and nitre; the vitriolic acid in the former case, and the nitrous
in the latter, giving place to the stronger vapour of spirit of salt.

The rust of iro