The Flow Of Gases In Furnaces

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2 APPLICATION OF THE LAWS OF HYDRAULICS
live and exist in a vacuum. It is this neglect of the part played
by the air which causes error; it is this which prevents a clear
conception of the mechanism of the circulation of the hot gases
within a reverberatory furnace. When the presence of the air
is taken into consideration, the problem becomes very clear.
What is it that forms the flame? It is a mixture of gases at a
high temperature, reacting upon each other (combustion) and
releasing in this manner a sufficient amount of heat to raise the
products of their combustion to incandescence. The solid par-
tides of carbon, by their incandesence, give to the flames that
especial appearance which impresses the imagination and causes
the flame to be attributed to some infernal power. But, in
reality, the idea which the author desires to convey in regard to
the " flame " may be better understood if the flame is considered
as a current of incandescent gas. This approximation is suffi-
ciently accurate for the purpose.
The reverberatory furnace is accordingly considered as an
apparatus immersed in a liquid, the air, which weighs 1 kg 29
per cubic meter, in the interior of which there circulates a current
of incandescent gases, that is to say, a liquid much lighter than
the air.
It is known that the coefficient of expansion of gases is -5--^-;
if, therefore, the specific weight of air at 0° is considered as unity:
at 273° its specific weight will be £
546° i
819° i
1092° i
1365° $
1638° i
1911° £
and as the specific weight of air at 0° is 1 kg 29:
'? at 273° its specific weight will be 0 kg 645
;« 546° 0 430
\ 819° 0 323
J 1092° 0 258
| 1365° 0 215
jj 1638° 0 184
i< 1911° 0 161