Gaseous carbon, on the other
hand, emits more heat than an equivalent quantity of hydrogen, [Footnote:
In a blowpipe flame hydrogen can only burn to gaseous, not liquid,
water.] even when it is only converted into the monoxide. In other words,
a gaseous fuel which consists of hydrogen alone can only yield that
temperature as a maximum at which the speed of the dissociation of the
water vapour reaches that of the oxidation of the hydrogen; and were
carbon dioxide the only oxide of carbon, a similar state of affairs would
be ultimately reached in the flame of a carbonaceous gas. But since in
the latter case the carbon dioxide does not tend to dissociate
completely, but only to lose one atom of oxygen, above the limiting
temperature for the formation of carbon dioxide, carbon monoxide is still
produced, because there is less dissociating force opposed to its
formation. Thus at ordinary temperatures the heat of combustion of
acetylene is 315.7 calories; but at temperatures where water vapour and
carbon dioxide no longer exist, there is lost to that quantity of 315.7
calories the heat of combustion of hydrogen (69.0) and twice that of
carbon monoxide (68.
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