AERO 
had all the fixed air found in the refiduum been contained in 
the original air, it muff have been at leaf!: one half heavier. 
“ Indeed (fays the doctor) if any quantity of inflammable 
air, of about the fame fpecific gravity with common air 
(which is the cafe, with that fpecies of it I am now confi- 
dering), yield fo much as feven-tenths of its bulk of fixed 
air in confequence of its explofion with dephlogifiicated 
air, it is a proof that at lead part of that fixed air was ge¬ 
nerated in the procefs, becaule feven-tenths of luch fixed 
air would weigh more than the whole meafure of inflam¬ 
mable air.” 
Numerous experiments, evincing dill farther the gene¬ 
ration of fixed air in thedecompotition of inflammable air, 
are defcribed by Dr. Priefiley, and with various refults, 
according to the procefles ufed, and the different fubdan- 
ces employed in procuring the latter. From the whole of 
them it was evident, that at leaf! part of the fixed air found 
after the explofion was produced by its means. But the 
following feem proofs no lefsconvincing that fixed air may 
be converted into the inflammable kind, or at leaf! that the 
elements of fixed air may remain in inflammable air in fuch 
a manner as to be imperceptible. On heating in an earth¬ 
en retort a quantity of flaked lime, which had long been 
kept dole corked in a bottle, it gave air, of which one- 
fifth was generally fixed air; but in the gun-barrel the 
fame lime yielded no fixed air, but a great quantity of in¬ 
flammable air of the explofive kind, like that which is got 
from iron alone by means of water. As this total difap- 
pearance of the fixed air appeared extraordinary, the doc¬ 
tor was induced to repeat it feveral times with all poilible 
care : and the following was the refult of his experiments: 
Three ounces of flaked lime, which had for fome time been 
expofed to the open air, heated in an earthen tube, yielded 
fourteen ounce-meafnres of air, of which only two and a 
half remained unabforbed by water ; the refiduum was 
flightly inflammable, but not perfectly phlogifticated. 
Three ounces of the fame lime, heated in a gun-barrel, 
gave twenty ounce-meafures of air, all of which was in¬ 
flammable, and no part fixed. It was expeCted, however, 
that the fixed air would have appeared on the decompofi- 
tion of this inflammable air with the dephlogifiicated kind : 
but after this procefs it appeared to be exactly fuch in¬ 
flammable air as is procured from metals by the mineral 
acids, or by fleam ; the diminution of the two kinds of air 
being exactly the fame : and, though fome fixed air was 
found in the refiduum, it was no more than is uf'ually met 
with in the decompofition of inflammable air procured by 
means of fpirit of fait.—Suppofing that the two kinds of 
air might incorporate, when one of them was generated 
within the other, a gun-barrel was filled with fixed air, 
and the clofed end of it put into a hot fire. Inflammable 
air was inflantly produced; but, when the fixed air was 
feparated from it, it burned like inflammable air with 
which no other kind had ever been mixed. 
On heating iron-turnings in five ounce-meafures of fixed 
air, the quantity of it was increafed about one ounce-mea- 
f'ure, and there remained one and J unabforbed by 
water. The experiment was repeated with the fame re¬ 
fult; and it was farther obferved, that, though the inflam¬ 
mable air procured in this manner did not appear by the 
ted of lime-water to contain any fixed air, yet, when it was 
decompofed by firing it with an equal quantity of dephlo¬ 
gidicated air, the refiduum contained one-third of fixed 
air. The diminution was to i-45. Hence thedoftor con¬ 
jectures, that though, in fome cafes, the fixed air appears 
to be generated by the decompofition of dephlogifiicated 
and inflammable air, yet that inflammable air, when thus 
produced in contaCt with fixed air, may combine with it, fo 
as to be properly contained in it, and in fuch a manner that 
it cannot be difeovered by lime-water. 
Inflammable air, when produced in the dried: way pofli- 
ble, is exceeuingly light, as has been already obferved ; 
but Dr. Priefiley has found, that, by handing on water, a 
very confiderable increase is made in its fpecific gravity ; 
fo that, from being ten or twelve times lighter than at- 
L O G Y. , 5S 
mofpherical air, it foon becomes only feven links lighter. 
This great propenfity to unite with water is alfo taken no¬ 
tice of by Mr. Kirwan ; who tells us, that the bulkof in'- 
flammable air obtained over water with the adidance of 
heat towards the end, was one-eighth greater than when 
produced over mercury; but that the weight of it in the 
former cafe was only eight or nine times lefs than common 
air.—“ From eighty-five cubic inches of inflammable air 
obtained over water, I extracted,” fays he, “ by oil of vij 
triol expofed to it for fifty-five hours, two grains of wa¬ 
ter; and, though undoubtedly there is an error in all thefe 
experiments, yet there can be little doubt but this inflam¬ 
mable air contained one-half its weight of water. The 
inflammable air, by the fubtraCtion of its water, lod its- 
fmell, but continued as inflammable as ever ; and there¬ 
fore there is no reafon to think that it was decompofed, or 
that water is any way eflential to it.” 
This conclulion is direCtly contrary to that of Dr. Prieff- 
ley, that water is an eflential ingredient in the compofition 
of inflammable air; nor do the experiments of the latter 
feem to have had any weight with. him. On the other 
hand, Dr. P. informs us, that “inflammable air feemx 
now to confid of water and inflammable air; which, how¬ 
ever, feems extraordinary, as the two fubdances are here¬ 
by made to involve each other; one of the condiment parts 
of water being inflammable air, and one of the condiment 
parts of inflammable air being water; and therefore, if 
the experiments would favour it (but I do not fee that they 
do fo), it would be more natural to fuppofe, that water, 
like fixed air, confids of phlogidon and dephlogidicated 
air, in fame diderent mode of combination. 
“There is an adonilhing variety in the different kinds 
of inflammable air, the caufe of which is very imperfectly 
known. The lighted, and therefore probably the pured, 
kind, feems to confid of phlogidon and water only. But 
it is probable that oil, and that of different kinds, may be 
held in folution in feveral of them, and be the reafon of 
their burning with a lambent flame, and alfo of their be¬ 
ing fo readily refolved into fixed air when they are decom¬ 
pofed by dephlogidicated air ; though why this thould be 
the cafe I cannot imagine. 
“ When inflammable and dephlogidicated air are burn¬ 
ed together, the weight of the water produced is never, I. 
believe, found quite equal to that of both kinds of air. 
May not the light, therefore, emitted from the flame, be 
part of the phlogidon of the inflammable air united to the 
principle of heat? And, as light accompanies the eleElric 
J'bark, may not this alfo be the real occafion of fome phlo- 
gidic matter, though it is not eafy to find the fource of it.” 
The French chemids, who deny the exidence of phlo- 
gifton, are of opinion, that inflammable air is a Ample un¬ 
compounded element. See Phlogiston. 
It has been proved by experiment, that inflammable air 
is abforbed by wa^erin confiderable quantity, and that, by 
the application of heat, it may be expelled again in equal 
quantity. Plants in general grow tolerably well in inflam¬ 
mable air, and the willow plant has been obferved to ab- 
forb great quantities of it. Its inflammability is not di- 
miniffted by the putrefaction of animal fubdances, nor 
does their putrefaction feem to be retarded by it. Ani¬ 
mals confined in it are killed almod as foon as in fixed air: 
but infeCts, which can live a confiderable time in phlogif¬ 
ticated air, live alfo a confiderable time in this. The Ab¬ 
be Fontana, having filled a large bladder with inflamma¬ 
ble air, began to breathe it. The fuff infpiration produ¬ 
ced a great oppreflion in his lungs, the fecond made him- 
look very pale, and the third was fcarcely accomplifhed 
when he fell on his knees through weaknefs. Birds and 
fmall quadrupeds, inclofed infmall veflels of thisair, died 
after a very few infpirations. Laftly,. inflammable air pof- 
fedes a final ler fhare of refraftive power than common air: 
as appears from Mr. Warltire’s experiment with an hol¬ 
low triangular prifm filled with it. 
The inflammability of this air has given occafion to va¬ 
rious projeCls, fuclr as lamps, &c» which may be lighted 
