and VI., acetylene
does not safely bear compression to a point exceeding 2 atmospheres; and
the liability to spontaneous dissociation or explosion in presence of
spark or severe blow, which is characteristic of compressed gaseous
acetylene, is greatly enhanced if compression has been pushed to the
point of liquefaction.
However, two methods of retaining the portability and convenience of
compressed acetylene with complete safety have been discovered. In one,
due to the researches of Claude and Hess, the gas is pumped under
pressure into acetone, a combustible organic liquid of high solvent power,
which boils at 56 deg. C. As the solvent capacity of most liquids for
most gases rises with the pressure, a bottle partly filled with acetone
may be charged with acetylene at considerable effective pressure until
the vessel contains much more than its normal quantity of gas; and when
the valve is opened the surplus escapes, ready for employment, leaving
the acetone practically unaltered in composition or quantity, and fit to
receive a fresh charge of gas. In comparison with liquefied acetylene,
its solution in acetone under pressure is much safer; but since the
acetone expands during absorption of gas, the bottle cannot be entirely
filled with liquid, and therefore either at first, or during consumption
(or both), above the level of the relatively safe solution, the cylinder
contains a certain quantity of gaseous acetylene, which is compressed
above its limit of safety.
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