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covers of books which were furnished to me at that time. If
you apply a little piece of the leather to your tongue, you will
taste its acidity ; and if it be treated with water or spirit of
wine and tested with a solution of baryta, it will be found
that the acid is sulphuric acid. These effects were observed
many years ago in the library of the Athenaeum Olub-House,
and they were growing to be so serious that the managers
requested a commision of chemists—including Mr. Faraday,
Mr. Brande, Dr. Prout, Mr. Aiken, and others—to inquire
into it, and I have before me a copy of their report on the
subject. It is to the effect that the mischief is clearly due to
the presence of sulphuric acid which had come from the
burning gas; and they state that the mischief will continue
so long as gas is used in the library without proper ventilation.
Mr. Faraday thereupon designed the system of ventilation
which is still used in the library. As to the effects of the
products of burning gas on shop goods, they are notorious,
for such goods are regularly disposed of as damaged or gassy
things. It has been remarked, too, that plants are quickly
killed by the products of burning gas, for thev are peculiarly
susceptible of injury from the presence of sulphurous acid in
the air. According to Drs. Christison and Turner, as little
as one part in 10,000 of air will kill plants in less than 24
hours. And you cannot use gas in a conservatory, either for
heating or for illuminating purposes, unless the products of
combustion are entirely removed. Dr. Christison has written
to me very strongly on this subject, and he attributes the
absence of flowers and plants from the rooms of Edinburgh to
the circumstance that gas is universally used in them,
Advancmg a step further in my inquiries, I ascertained that
the water produced by burning gas, collect it how you will, is
always acid, and will rot leather, paper, cotton/and linen,
Here are specimens of such tissues, which have been dipped
in the condensed liquid products of gas combustion, and you
Will observe that they are as rotten as tinder Lastly, I
trived a plan wherby the amount of sulphur in coal gas could
be estimated. I had thought that the instrument was