e flask with my fire-air. It was pleasing to
observe how the water rose gradually into the flask; and how the flame
went out when 7/8 of the flask were full of water.

+47. Sixth Experiment.+--I laid some glowing coals upon the stand (Sec. 21,
letter _c_), and placed over them a flask which was filled with
fire-air. The coals had not even reached the air in the flask before
they began to burn very brilliantly.

After everything had become cold, I made an aperture under the flask,
whereupon the fourth part became filled with water. But when I removed,
by means of milk of lime, the aerial acid which was present in the
residual air (Sec. 22) there remained in the flask only the fourth part. In
this air a candle could still burn.

+48. Seventh Experiment.+--I also examined the behaviour of fire-air
with sulphur (Sec. 23). As soon as the burning sulphur came into contact
with the fire-air contained in the flask, the flame became much larger
and brighter. When this fire had gone out, the water in the dish had
found a way to come through the mass into the flask, which became 3/4
filled with it. As I employed for these last 3 experiments a flask which
was only of 30 ounces measure, I was obliged to arrange the stand (Sec. 21)
to suit.

+49.+ I have mentioned (Sec. 16) that I found vitiated air lighter than
ordinary air. Must it not follow from this that the fire-air is heavier
than our air? As a matter of fact, I actually found, when I accurately
weighed as much fire-air as occupied the space of 20 ounces of water,
that this was almost 2 grains heavier than the same bulk of common air.

+50.+ These experiments shew, therefore, that this fire-air is just that
air by means of which fire burns in common air; only it is there mixed
with a kind of air which seems to possess no attraction at all for the
inflammable substance, and this it is which places some hindrance in the
way of the otherwise rapid and violent inflammation. And in fact, if air
consisted of nothing but fire-air, water would surely render small
service in extinguishing outbreaks of fire. Aerial acid mixed with this
fire-air, has the same effect as vitiated air. I mixed one part of
fire-air with 4 parts of aerial acid; in this mixture a candle still
burned moderately well. The heat which lurks in the small interstices of
the inflammable substance cannot possibly make up so much heat as is
felt in fire; and I think I am not mistaken when I conclude from my