What has been said in the preceding paragraph about the temperature at
which acetylene decomposes is only true when the gas is free from any
notable quantity of air. In presence of air, acetylene inflames at a much
lower temperature, viz., 480 deg. C. In a manner precisely similar to that
of all other combustible gases, if a stream of acetylene issues into the
atmosphere, as from the orifices of a burner, the gas catches fire and
burns quietly directly any substance having a temperature of 480 deg. C. or
upwards is brought near it; but if acetylene in bulk is mixed with the
necessary quantity of air to support combustion, and any object exceeding
480 deg. C. in temperature comes in contact with it, the oxidation of the
hydrocarbon proceeds at such a high rate of speed as to be termed an
explosion. The proportion of air needed to support combustion varies with
every combustible material within known limits (_cf._ Chapter VI.),
and according to Eitner the smallest quantity of air required to make
acetylene burn or explode, as the case may be, is 25 per cent. If, by
ignorant design or by careless manipulation, the first batches of
acetylene evolved from a freshly charged generator should contain more
than 25 per cent.
Pages:
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119