128 Mr, Cavennisn's Experiments on Air. 
either in the diminution. which, they fuffered by the explofion, 
or the teft of the burnt air. | 
From the fourth experiment it appears, that 423 meafures of 
inflammable air are nearly fufficient to completely phlogifticate 
1000 of common air; and that the bulk of the air remaining 
after the explofion is then very little more than four-fifths of 
the common air employed; fo that as common air cannot be 
reduced to a much lefs bulk than that by any method of phlo- 
giftication, we may fafely conclude, that when they are mixed 
in this proportion, and exploded, almoft all the inflammable 
air, and about one-fifth part of the common air, lofe their 
elafticity, and ate condenfed into the dew which lines the 
glafs. 
The better to examine the nature of this dew, 506600 grain 
meafures of inflammable air were burnt with about 24 times 
that quantity of common air, and the burnt air made fo pafs 
through a glafs cylinder eight feet long and three-quarters of 
an inch in diameter, in order to depofit the dew. The two 
airs were conveyed flowly-into this cylinder by feparate cop- 
per pipes, paffing through a brafs plate which {topped up the 
end of the cylinder; and as neither inflammable nor common 
air can burn by themfelves, there was no danger of the flame 
{preading into, the magazines from which théy were conveyed. 
Each of thefé magazines confifted of a large tin veflél, in- 
verted into another: veflel juft big enough to! receive ‘it. The 
inner: veffel communicated with the copper pipe, and the air 
was forced out of it by pouring water ifito the outer veffel'; — 
and in order that the quantity of eommoniair expelled ‘thould 
be 2! times that’ of the inflammable, the water was let into 
the outer veflels by two holes in, the bottom of the fame tin’ 
pally the hole which conveyed the water into that veffel in 
which 
