It may be observed that
as the solution of acetylene in acetone is a liquid, the acetylene must
exist therein as a liquid; it is, in fact, liquid acetylene in a state of
dilution, the diluent being an exothermic and comparatively stable body.
The specific heat of acetylene is given by M. A. Morel at 0.310, though
he has not stated by whom the value was determined. For the purpose of a
calculation in Chapter III. the specific heat at constant pressure was
assumed to be 0.25, which, in the absence of precise information, appears
somewhat more probable as an approximation to the truth. The ratio
(_k_ or C_p/C_v ) of the specific heat at constant pressure to that
at constant volume has been found by Maneuvrier and Fournier to be 1.26;
but they did not measure the specific heat itself. [Footnote: The ratio
1.26 _k_ or (C_p/C_v) has been given in many text-books as the value
of the specific heat of acetylene, whereas this value should obviously be
only about one-fourth or one-fifth of 1.26.
By employing the ordinary gas laws it is possible approximately to
calculate the specific heat of acetylene from Maneuvrier and Fournier's
ratio. Taking the molecular weight of acetylene as 26, we have
26 C_p - 26 C_v = 2 cal.
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