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22
appendix.
Further extracts from Dr. Odling's Lecture.
* "So much, then, with regard to the ammonia as existing
in coal gas; and now to consider the sulphur. As all gas
contains ammonia, so all gas contains sulphur in greater or
less proportion. When this sulphur burns it gets converted
into what is termed sulphurous acid, and when this sulphurous
acid is exposed for a sufficient length of time to the air
it takes up more oxygen, and gets converted into sulphuric
acid, which, in a concentrated form, is known as oil of vitriol.
But no matter under what circumstances you burn sulphur,
it does not burn directly into sulphuric acid—it only burns
into sulphurous acid. No matter at what temperature you
burn the gas, you get sulphurous acid produced, and not
sulphuric; but when this sulphurous acid is exposed to the
air and to moisture, under these circumstances it absorbs
oxygen, and gets converted into sulphuric acid, and it is
possible that, under certain circumstances, supposing the
sulphuric acid to be so formed, it might get to a reasonable
degree of concentration.
" One word as to the character of this sulphurous acid. It
is a substance which, in a concentrated state, is very irritating.
Now-a-days we do not meet with sulphur matches,
they are generally tipped with paraffin, though most of us
know the irritating effect upon the nose of sulphurous acid;
but, though very irritating, it is not at all corrosive. As
medical men, we all understand the difference, that such a
thing as cantharides or snuff, for instance, is extremely irritating,
but yet not corrosive. Just so with sulphurous acid.
chemically speaking, it is one of the weakest acids with
which we are acquainted, and corresponds, in respect to
acidity, most nearly with that very feeble acid, carbonic acid.
* Note.- The following part of Dr. Odling's Lecture immediately precede
the part extracted by the company, and given at p. 10.