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it is two or three grains over; very frequently a few grains
under. At the same time, when we perform the experiment,
not in this way, but in a strictly chemical way, in a way in
which it would be performed in a laboratory, under these
circumstances we find the sulphur habitually to exceed the
20 grains allowed by the Act of Parliament; although, as I
have said, when we have regard to the products of combustion
yielded when the gas is burnt in an apparatus of this kind,
we find it affords an amount of sulphurous acid or sulphate
of ammonia corresponding with the average amount of 20
grains allowed by the Act of Parliament, and sometimes less.*
* * * *
| " But now comes the question of the conversion of the
sulphurous into sulphuric acid. That, first of all, is not a
rapid process. It is very rapid indeed so far as regards a
partial conversion, for it is very difficult to have sulphurous
acid in the air without a proportion of it being converted into
sulphuric acid; but you must remember, when dealing with
these minute proportions, that the minute proportions of
other substances existing in the atmosphere become similarly
important, and particularly the proportion of ammonia. It
would appear that the amount of ammonia existing even
in the open atmosphere is sufficient to neutralize the amount
of sulphuric acid formed under the circumstances of gas
combustion; but in a room where a large amount of gas is
burning a room crowded with human beings—the exhalations
give out an excess of ammonia, which would be sufficient
to 1 iii more than neutralize any amount of sulphurous acid
that might chance to get converted into sulphuric acid. Of
course, if you set to work with a view to convert the sulphurous
acid gas into sulphuric acid, you can readily do it. If
you cause such a burner as this to burn under a vessel which
is Kept cold by having a free current of water passing through
* Note.- Here follws the part of Dr. Odling's Lecture extracted by the
Company. See p. 10.
†This part of Dr. Olding's Lecture immediately followed the part extracted
by the company. See p. 13.