, that being highly toxic, as they
undoubtedly are, the gas containing them might be extremely dangerous to
breathe if it escaped from the service, or from a portable lamp,
unconsumed. Anticipating what will be said in a later paragraph, the
worst kind of calcium carbide now manufactured will not yield a gas
containing more than 0.1 per cent. by volume of sulphuretted hydrogen and
0.05 per cent. of phosphine. According to Haldane, air containing 0.07
per cent. of sulphuretted hydrogen produces fatal results on man if it is
breathed for some hours, while an amount of 0.2 per cent. is fatal in 1-
1/2 minutes. Similar figures for phosphine cannot be given, because
poisoning therewith is very rare or quite unknown: the cases of "phossy-
jaw" in match factories being caused either by actual contact with yellow
phosphorus or by inhalation of its vapour in the elemental state.
However, assuming phosphine to be twice as toxic as sulphuretted
hydrogen, its effect in crude acetylene of the above-mentioned
composition will be equal to that of the sulphuretted hydrogen, so that
in the present connexion the gas may be said to be equally toxic with a
sample of air containing 0.
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