Thus it appears that if the heat
evolved during the decomposition of calcium carbide is not otherwise
consumed, it is sufficient in amount to vaporise almost exactly 3 parts
by weight of water for every 4 parts of carbide attacked; but if it were
expended upon some substance such as acetylene, calcium carbide, or
steel, which, unlike water, could not absorb an extra amount by changing
its physical state (from solid to liquid, or from liquid to gas), the
heat generated during the decomposition of a given weight of carbide
would suffice to raise an equal weight of the particular substance under
consideration to a temperature vastly exceeding 438 deg. C. The temperature
attained, indeed, measured in Centigrade degrees, would be 438 multiplied
by the quotient obtained on dividing the specific heat of water by the
specific heat of the substance considered: which quotient, obviously, is
the "reciprocal" of the specific heat of the said substance.
The analogy to the combustion of coal mentioned on a previous page shows
that although the quantity of heat evolved during a certain chemical
reaction is strictly fixed, the temperature attained is dependent on the
time over which the reaction is spread, being higher as the process is
more rapid.
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