y of gunpowder fired in it will be wholly retained by it,
no part escaping into the common air.

Making an agitation in this air, the surface of it, (which still
continues to be exactly defined) is thrown into the form of waves, which
it is very amusing to look upon; and if, by this agitation, any of the
fixed air be thrown over the side of the vessel, the smoke, which is
mixed with it, will fall to the ground, as if it was so much water, the
fixed air being heavier than common air.

The red part of burning wood was extinguished in this air, but I could
not perceive that a red-hot poker was sooner cooled in it.

Fixed air does not instantly mix with common air. Indeed if it did, it
could not be caught upon the surface of the fermenting liquor. A candle
put under a large receiver, and immediately plunged very deep below the
surface of the fixed air, will burn some time. But vessels with the
smallest orifices, hanging with their mouths downwards in the fixed air,
will _in time_ have the common air, which they contain, perfectly mixed
with it. When the fermenting liquor is contained in vessels close
covered up, the fixed air, on removing the cover, readily affects the
common air which is contiguous to it; so that, candles held at a
considerable distance above the surface will instantly go out. I have
been told by the workmen, that this will sometimes be the case, when the
candles are held two feet above the mouth of the vessel.

Fixed air unites with the smoke of rosin, sulphur, and other electrical
substances, as well as with the vapour of water; and yet, by holding the
wire of a charged phial among these fumes, I could not make any
electrical atmosphere, which surprized me a good deal, as there was a
large body of this smoke, and it was so confined, that it could not
escape me.

I also held some oil of vitriol in a glass vessel within the fixed air,
and by plunging a piece of red-hot glass into it, raised a copious and
thick fume. This floated upon the surface of the fixed air like other
fumes, and continued as long.

Considering the near affinity between water and fixed air, I concluded
that if a quantity of water was placed near the yeast of the fermenting
liquor, it could not fail to imbibe that air, and thereby acquire the
principal properties of Pyrmont, and some other medicinal mineral
waters. Accordingly, I found, that when the surface of the water was
considerable, it always acquired the pleasant acidulous