A I R 
airing myfclf on the tops of the mountains, I fell into a 
profound contemplation on the vanity of human life. Ad- 
difon.^—T o air liquors; to warm them by the fire : a term 
ufed in converfation. To breed in nefts. In this fenfe, 
it is derived from aerie , a neft. It is now out of ufe. 
Air,/, in medicine, &c. makes one of the fix non-natu¬ 
rals.—From obfervations on bleeding in rheumatifms, and 
after taking cold, it is evident the air can enter with all 
its qualities, and vitiate the whole texture of the blood 
and other juices..—From the palfies, vertigoes, and other 
nervous affeiftions, caufed by damps, mines, See. it is evi¬ 
dent, that air thus qualified can relax and obftruft the 
whole nervous fyftem. And from the colics, fluxes, 
coughs, and confumptions, produced by damp, moift, and 
nitrous, air, it is evident it can corrupt and fpoil the no- 
bleft organs of the human frame. 
Circulation of Air in Rooms. To render the circulation 
of air fenfible, let the air of a room be heated by a ftrong 
fire, whilftthe air of a contiguous room is cold; then let 
the door between thefe two rooms be opened, in which 
cafe the hotair of one room, being lighter, will pafs through 
the upper part of the opening of the door into the cold 
room; and, on the contrary, the cold air ot the other 
room, being heavier, will pafs into the former roomthrough 
the lower part of the opening; accordingly, it will be 
found, that applying a lighted candle at the top, in the 
middle, and at the lower part, of the opening between the 
two rooms, a ftrong current of air will appear to pafs 
from the hot into the cold room near the top; a contrary 
current of air will appear to pafs from the latter into the 
former room near the lower part of the faid opening; 
whilft in the middle there is little or no motion at all, as 
may be clearly perceived by the direction of the flame of 
the candle. 
It is for the fame reafon that when the fire is lighted in a 
chimney, a ftrong current of air is occafioned to enter the 
room, which may be felt by applying the hand near the 
key-hole, or other fuch fmall openings, if the doors and 
windows are fliut; for the air over the fire being heated 
becomes lighter, and afeends into the chimney, confe- 
quently other colder air muft fupply its place, which for¬ 
ces its way through all the fmall openings it can find. 
Were a room with a fire in it to be perfectly clofed, ex¬ 
cepting the chimney, the air in it would foon become un- 
vvholefome for refpiration, and the fire would be foonex- 
tinguifhed, befides other inconveniences. Hence it ap¬ 
pears, that thofe perfons miftake who expeft to keep the 
air of a room fweetand wholefome, efpecially forconvalef- 
cents, by accurately flopping all the fmalleft openings that 
admit frefh air. When the current of air that enters in, 
to a room is on fome fide of it where it falls immediately 
upon the perfons who fit in the room, then it may be of- 
fenfive, efpecially to delicate conftitutions. In that cafe, 
fuch opening ftiould be clofed : but at the fame time ano¬ 
ther opening ftiould be made, for admitting frefh air, in 
a more convenient part; for a circulation of air, efpecial¬ 
ly in rooms, where a fire is kept, is not only falutary and 
ufeful, but abfolutely neceirary. 
It is a.vulgar error among many people, to believe that 
fire purifies the contaminated air, by deftroying the nox¬ 
ious particles mixed with it; and for this reafon they 
think, that the fire kept in a room where the air is tainted 
purifies the room, by rendering the air in it again fit for 
refpiration. Indeed, a fire kept in a room or apartment 
where the air is tainted, as is the cafe with hofpitals, 
gaols, and the like, does certainly purify the apartment, 
and the praftice is very ufeful; but, this efteft is only 
becaufe the fire promotes the circulation of the air, and 
dries the dampnefs of rooms, furniture, &c. fo that it is 
not the infe&ed air that is purified, but it is new, frefh, and 
wholefome air, that by the aftion of the fire has taken 
the place of the infefted air; which infected air, being 
rarefied by the heat, has been expelled from the apart¬ 
ment. Fire and combuftion in general is fo far from pu¬ 
rifying contaminated air, that it attually contaminates a 
Vql. I. No. 14. 
A I R zi 7 
prodigious quantity of it in a fliort time; fo that not only 
a common fire, but even a lighted candle, when kept in 
a well-clofed room, wherein the external air has not ac- 
cefs, inftead of purifying, renders the air of that room 
noxious. 
_A method has been lately invented, and a patent ob¬ 
tained, by Mr. Jofeph Green, of Wandfworth, near 
London, for warming rooms and buildings with hot air of 
a more pure quality than has hitherto been ufed. The 
principle on which this invention is founded is the heat¬ 
ing air, for the purpofe of warming buildings, by means 
of hollow veflels, or pipes, immerfed in hot water or 
fleam, whereby too great a degree of heat is avoided, and 
the air remains unburnt, and fit for refpiration, “ For 
thispurpofe,” fays the patentee, “I provide a boiler made 
of iron, copper, or other fit materials, with a cover faf- 
tened thereto. Within the boiler I fix a hollow veil'd or 
worm, and fometimes feveral fuch veflels or worms, made 
of lead, copper, earthen ware, or other proper materials; 
and into each of thefe hollow veflels or worms I introduce 
the external or open air, by the medium of a pipe, which 
I make to pafs through a convenient part of the boiler, 
firmly foldered or cemented into it; and which pipe I 
communicate with the faid veflels or worms. The boiler 
may be fixed in the ordinary manner iaany of the lower 
apartments, or other convenient part of the houfe or 
buildings; or it may be fixed behind a ftove or grate, fo 
as to be heated by means of a common fire, in any of the 
rooms, and the lize of it ftiould be regulated by the ex¬ 
tent of the building propofed to be warmed. From the 
hollow veflels or worms, pipes are fixed, and carried, in the 
molt convenient manner, to the different rooms, or parts 
of the buildings, to which the warm air is to be convey¬ 
ed. To thefe pipes are fixed cocks or Aiders, in order to 
admit, or prevent, the introduction of the warm air into 
any particular room or place; and in fome convenient part 
of the pipes I place a fluffing valve, or felf-atting cock, 
to prevent the burfting of the boiler, or pipes, by the 
force of the fleam. The boiler being in part filled with 
water, a fire is lighted in the furnace, and the water made 
to boil, or brought to fuch a degree of heat as may be 
found neceirary; by this heat the air contained in the hol¬ 
low veflels or worms before-mentioned, being rarefied 
and warmed, will afeend, and is to be admitted, by means-’ 
of the above-mentioned cocks or Aiders, or by any other 
convenient mode, into the feveral apartments to be warm¬ 
ed. When the rooms are at too great a diflance from the 
boiler to be warmed by Angle pipes, then, in order to 
prolong the direftion of the heat, I either inclofe the 
pipes, through which the warm air is conveyed, in large 
pipes, to which the fleam rifes from the boiler, or I in¬ 
troduce the warm air into the larger and the fleam into 
the fmaller pipes; by which means the air-pipes are pre¬ 
vented from growing cool fo foon as they would do if they 
were expofed to the aftion of the open air. I alfo in cer. 
tain cafes, where I judge it proper and more convenient, 
place my air-veflel or worm in a veflel diftinft from the 
boiler, but ftill having a communication therewith for 
the fleam from the boiler to pafs, and thus heat the air- 
veflel or worm by means of fleam only; by the above pro- 
cefs too great a degree of heat is avoided, and the air re¬ 
mains unburnt, and fit for refpiration. The patent for 
this invention is dated Dec. 9, 1793. 
Air-balloons, a general name given to bags of any 
light fubftance filled with inflammable air, or other per¬ 
manently elaflic fluid, whofe fpecific gravity isconfidera- 
bly lefs than that of common atmofpheric air. The eon- 
fequence of their being filled in this manner is, that, if they 
are of any conliderable magnitude, they afeend in the air 
to an amazing height; and will not only afeend in this 
maimer by themfelves, but carry up along with them 
great weights, and continue to rife till they attain an 
height in which the circumambient air is of the fame fpe- 
cific gravity with themfelves. In this fitnation they will 
either float or be driven in the direftion of the wind or 
3 K current 
