and allowed it to fall into the jar of carbonic acid, when it floated in
it midway.] It is floating, as the balloon floated, by virtue of the
greater weight of the carbonic acid than of the air. And now, having so
far given you the history of the carbonic acid as to its sources in the
candle, as to its physical properties and weight when we next meet I
shall shew you of what it is composed, and where it gets its elements
from.
LECTURE VI.
CARBON OR CHARCOAL COAL-GAS RESPIRATION AND ITS ANALOGY TO THE BURNING
OF A CANDLE CONCLUSION.
A lady, who honours me by her presence at these Lectures, has conferred a
still further obligation by sending me these two candles, which are from
Japan, and, I presume, are made of that substance to which I referred in a
former lecture. You see that they are even far more highly ornamented than
the French candles; and, I suppose, are candles of luxury, judging from
their appearance. They have a remarkable peculiarity about them namely, a
hollow wick, that beautiful peculiarity which Argand introduced into the
lamp, and made so valuable. To those who receive such presents from the
East, I may just say that this and such like materials gradually undergo a
change which gives them on the surface a dull and dead appearance; but
they may easily be restored to their original beauty, if the surface be
rubbed with a clean cloth or silk handkerchief, so as to polish the little
rugosity or roughness: this will restore the beauty of the colours. I have
so rubbed one of these candles, and you see the difference between it and
the other which has not been polished, but which may be restored by the
same process. Observe, also, that these moulded candles from Japan are
made more conical than the moulded candles in this part of the world.
I told you, when we last met, a good deal about carbonic acid. We found,
by the lime-water test, that when the vapour from the top of the candle or
lamp was received into bottles, and tested by this solution of lime-water
(the composition of which I explained to you, and which you can make for
yourselves), we had that white opacity which was in fact calcareous
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