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47
SULPHUR IMPURITIES IN GAS.
(Special Report presented to the Council on March 15th, 1906.)
Illuminating gas is obtained by the destructive distillation
of coal in retorts, without access of air. Coke is produced
and various volatile products are given off, e.g., compounds
of carbon and hydrogen, of carbon and oxygen, of carbon
and sulphur, of sulphur and oxygen, of sulphur and
hydrogen, and of nitrogen and hydrogen; whilst tar and an
ammoniacal liquor are also produced. The gases are purified
at the Gas Works first by condensation and washing, then
by being passed through coke scrubbers and iron purifiers,
and afterwards being treated with lime. In this way, sulphur
and ammonia compounds are separated out, and got
rid of—at least, in great part. When properly purified, coal
gas should contain on an average :—hydrogen, 45 per cent.;
marsh gas, 35 per cent. ; carbonic oxide, 6 per cent. ; illuminants
(ethylene, acetylene), 6 per cent.; carbonic acid, 3 per
cent.; nitrogen and sulphurous acid, etc., 5 per cent.
The sulphur compounds (chief of which are sulphurous
and sulphuric acids) are the principal impurities of gas.
Sulphurous and sulphuric acids have a very destructive
effect on vegetation, mortar, and the softer kinds of building
stones. They do not appear to have any known marked
effect on healthy people, but the sulphurous acid is a source
of danger to persons with weak or diseased lungs, e.g.,
those suffering from asthma, bronchitis, consumption, etc.
Sulphuretted hydrogen (a compound of sulphur and hydrogen)
is poisonous, and, consequently, a danger to the health
of persons inhaling it. It is met with in badly purified coal
gas, requiring special precautionary measures to be taken
by Gas Companies. When inhaled, it depresses vitality, and
is specially obnoxious to infant life. In this connection it
will be noted that recent Acts dealing with sulphur impurities
in gas only impose penalties upon Gas Comp inies pro-