i 62 AERO 
capacity of the bottle which contains this air be nearly 
equal to four ounce-meafures, and the flame of a candle 
be applied to its mouth, it will burn quietly for about 
half a minute, the flame gradually defcending lower and 
lover, in proportion as the inflammable gas is confumed. 
Hence we fee, that inflammable air, like all other combuf- 
tible fubftances, burns only when in contaCt with common 
air; fo that, if the bottle be doled, the flame is put out 
immediately, becaufe the airis intercepted. But, if the in¬ 
flammable air be put in fuch a fituation as to expofe a ve¬ 
ry great fur race to the common air, it is plain, that by this 
means its combullion will be accelerated, fo as to go off 
with anexplofion, caufed by the fudden rarefaction of the 
air. This circumfhjnce lias given occalion to the very en¬ 
tertaining experiment with what has been called the elec¬ 
trical pilloi. This inftrument confifts of a liollow brafs 
ball with a narrow mouth, into which a mixture of inflam¬ 
mable and atmofpheric air is introduced, and the mouth 
of the pilloi afterwards corked very firmly. Through the 
end immediately oppolite to the mouth, a glafs tube is 
palled, and through that a piece of wire, which, being- 
bent downwards, approaches within a draw’s breadth of 
the inner furface of the ball. Along this wire an eledtric 
lpark is conveyed, which, fetting the inflammable air on 
fire, occalions a loud explolion, and forces the cork out of 
the mouth of the piflol with conliderable violence. 
By taking eledlric fparks in any kind of oil, fpirit of 
wine, ether, or fpirit of fal ammoniac* Dr. Priedley ob¬ 
tained inflammable air. The oil, or other liquor, was 
confined in a glafs tube by quickfilver, and a wire was ce¬ 
mented in the upper part of the tube, through which the 
fparks, being rent, went to the quickfilver through the oil. 
After a few fparks had been taken, a quantity of inflamma¬ 
ble air was generated. Thiselaflic fluid does not lofe its 
inflammability by being palled feveral times from one vef- 
fel into another through water.—Alkaline air, by taking 
eledlric explofions in it, is changed into inflammable air. 
If iron is put into a llrong vitriolic acid, the quantity 
of elaftic fluid produced is very little, except heat be ap¬ 
plied. But this eladic fluid is vitriolic acid air, mixed 
with a fmall proportion only of inflammable air, which is 
always lefs when the acid is more concentrated.—Zinc, 
treated after the fame manner, produces the like effebts, 
except that it gives more eladic fluid, without the appli¬ 
cation of heat, than iron does ; and the greateflpart of the 
produced eladic fluid is inflammable.—In order to obtain 
the greated. quantity of inflammable air from iron or zinc, 
the vitriolic acid mud be diluted with five or fix parts of 
water. Dr. Priedley found, that eleven grains of iron 
yielded eight and a quarter ounce-tneafures of inflamma¬ 
ble air. According to Mr. Cavendifli, one ounce of zinc, 
diffolved either in the vitriolic or marine acid, yields a 
quantity of inflammable air equal to the bulk of 356 oun¬ 
ces of water ; one ounce of iron, diffolved by means of vi¬ 
triolic acid, yields a quantity of inflammable air equal to 
the bulk of 412 ounces of water; and one ounce of tin 
yields half as much inflammable air as iron does.—The 
folutions of iron, tin, copper, lead, and zinc, in the 
marine acid, produce marine acid air, and inflammable 
air, but in various quantities. The proportion of the 
former to the latter is as one to eight in iron, as one to fix 
in tin, as three to one in copper and lead, and as one to 
ten in zinc. Regulus of antimony, diffolved in marine 
acid, with the application of heat, yields a fmall quantity 
of elaflic fluid, which is weakly inflammable. 
Dr. Priedley obtained inflammable air, not only bydif- 
folving various fubflances in marine acid, but alfo by ex- 
pofing divers bodies to marine acid air, which is probably 
thepureft part of the marine acid. Having admitted iron- 
filings to this acid air, they were diffolved by it pretty fall; 
half of the elaltic fluid difappeared, and the reft was ren¬ 
dered unabforbable by water, and inflammable. The 
fame effect was produced by almoft every fubftance which 
contains phlogifton.—It feems in faCt, as if this acid air, 
having a great affinity with phlogifton, feparates it from 
3 
LOG Y. 
all thofe fubftances which contain it even in fmall quantify 
and from that combination becomes inflammable. 
By means of nitrous acid, inflammable air may be ob¬ 
tained from various fubftances containing phlogifton ; but 
it is always mixed with nitrous air, and fometimes alfo 
with fixed and common or phlogiftieated air. If two parts 
of fpirit of wine, mixed with one part of nitrous acid’, are- 
put into a vial with a ground ftopple and tube, and the 
flame of a candle be applied to it, fo as to heat it gra¬ 
dually, the inflammable air will be produced very rea¬ 
dily ; the inflammability of which is, how ever, not very 
permanent, for by a little waffling in. water it stray be an¬ 
nihilated. 
To produce Nitrous Air. This permanently-elaftic fluid 
is never found naturally, like fixed or inflammable air, 
but is entirely artificial.—Silver, copper, brafs, iron, mer¬ 
cury, bifmuth, nickel, See. when mixed with nitrous acidi, 
yield nitrous air in great quantity. Some of them, efpe- 
cially mercury, require the aid of hear ; -for feme, the 
flame of a candle applied to the vial is fufficient: but 
others, efpecially copper and iron, do not want any heat. 
Gold, platina, and regulusof antimony, when put in aqua 
regia, yield nitrous air pretty readily. Among the metals, 
lead yields it in the fmalleft quantity. Among the- femi- 
metals, zinc gives the weakeft nitrous air, when dilfolved in 
nitrous acid. The elaftic fluid produced from it is moft- 
ly phlogiftieated air. From four pennyweights and feven- 
teen grains of zinc, diffolved in fpirit of nitrediluted with 
an equal quantity of water, Dr. Priedley obtained about 
twelve ounce-meafures of very weak nitrous air. He alfa 
obtained nitrous air even from fome flowers of zinc. 
The quantity of nitrous air that may be obtained from 
metals is difficult to afeertain, on account of the neceffai f' 
diverfity of the ftrength of the acid, the peculiar nature of 
the metal, and the method of performing the experiments-. 
The following table of the produce of nitrous air from va¬ 
rious metals is taken from Dr. Prieftley, who neverthelefs 
intimates that it is far from being accurate. 
dwts. 
6 
g rs. 
0 
of filver yielded 17^ ounce-meafures.. 
5 
*9 
of quickfilver, 4^ 
1 
of copper; 14^ 
2 
0 
of brafs. 21 
0 
20 
of iron, :-6 
of bifmuth, 6 
r 
5 
0 
1 2. 
of nickel, 4 
The degree of ftrength of the acid oceafions great cli- 
verfity in the production of nitrous air. Copper dilfolved 
in ftrong nitrous acid w ill not produce the lead quantity of 
nitrous air; but, when diffolved in nitrous acid diluted 
with two or three parts of water, it produces a great 
quantity. 
For the generality of experiments, no degree of exter¬ 
nal heat is required, except mercury be ufed. Copper or 
brafs, in flat feales, two or three grains in weight, and 
about a quarter of a fquare inch in furface, when diffolv- 
ing in diluted nitrous acid, yields nitrous air very equably ; 
but, if iron be ufed, the pieces of it lhould be larger and 
fewer; in fhort, it fhould prefent a much lefs furface to 
the diluted acid ; otherwife the increafe of heat in the 
procefs, and the rapid production of elaftic fluid, render 
the operation both difficult and hazardous. 
As nitrous air is moll ufed to try the goodnefs of refpira.- 
ble air, it is of great confequence to make it always of one 
uniform degree of purity. Accordingly, brafs yields nk- 
trousair of a more uniform quality than iron : copper ex¬ 
cels brafs ; but pure mercury is ftill fuperior to copper : 
and indeed this is the metal which, coniiderirsg its nature, 
uniformity of fubftance, and eafv folution,. is upon the 
whole the moll tifeful for this purpofe. 
To make Nitrous Air. The whole procefs is the fame as 
that deferibed for Fixed Air. Fill about one third of the 
bottle with, copper, brafs, or quickfilver, then add as much 
water as will cover the metal filings, or in proportion if 
quickfilver is uled ; and laftly, the nitrous acid, in quan¬ 
tity 
