5 deg. C.
and 762 mm., which is equivalent to 1403.7 litres (= 49.57 cubic feet) at
15 deg. C. and 760 mm. (or 60 deg. F. and 30 inches; there is no appreciable
change of volume of a gas when the conditions under which it is measured
are altered from 15 deg. C. and 760 mm. to 60 deg. F. and 30 inches, or
_vice versa_).
The yield of gas from this sample is therefore 1403.7/4.840 = 290 litres
at 15 deg. C. and 760 mm. per kilogramme, or 49.57/10.67 = 4.65 cubic feet at
60 deg. F. and 30 inches per pound of carbide. The apparatus described can,
of course, be used when smaller samples of carbide only are available for
gasification, but the results will be less trustworthy if much smaller
quantities than those named are taken for the test.
Other forms of carbide-to-water apparatus may of course be devised, which
will equally well fulfil the requisite conditions for the test, viz.,
complete decomposition of the whole of the carbide without excessive rise
of temperature, and no loss of gas by solution or otherwise.
An experimental wet gas-motor, of which the water-line has been
accurately set (by means of the Gas Referees' 1/12 cubic foot measure, or
a similar meter-proving apparatus), may be used in place of the graduated
gasholder for measuring the volume of the gas evolved, provided the rate
of flow of the gas does not exceed 1/6 cubic foot, or say 5 litres per
minute.
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