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it, the bottom of the vessel is constantly covered with a layer
of moisture; the sulphurous acid gets condensed in this
moisture, and a portion of it converted into dilute sulphuric
acid, which gradually becomes concentrated acid. In this
way you may produce a certain quantity of sulphuric acid by
the combustion of gas; but, when gas is burnt under ordinary
conditions, so as to diffuse its products into the atmosphere,
the produced sulphurous acid can only form about a
thousandth part of the carbonic acid gas existing in the room
as a product of gas combustion, even upon the excessive
assumption that the gas contains double the amount of
sulphur allowed by the standard of the Act of Parliament."
In the discussion which followed Dr. Odling's Lecture, Dr.
Letheby is reported in the same Gas Journal to have said on
the subject of sulphur, as follows :—
"And now I am desirous of making a few remarks on the
effects of the sulphur in coal gas. Dr. Odling has directed
your attention to this matter from a statistical point of view,
and has shown you how, by a mathematical process, the
amount of sulphur acids in the products of burning gas may
be reduced to a vanishing point, and that, therefore, they
must be insignificant and wholly harmless; but I will ask
you to look at the subject from another point of view, and to
examine it by the light of facts as well as of figures. About
15 or 20 years ago, when I began to enquire into this matter,
I was struck with a circumstance which is now, as it was
then, very remarkable—namely, that wherever gas is burnt
continuously, and in large quantity, it causes a rapid destruction
of textile fabrics, with a verv acid condition of them.
This is notably so in our public libraries, and in warehouses
and shops. I obtained so many striking proofs of this, especially
from the libraries of the Athenaeum Club-House, the
London Institution, the College of Surgeons, and elsewhere,
that I made them the subject of a special report to the City
authorities in 1854 ; and here you will see the specimens of