Just now you saw that one end of this battery took hold of the copper,
extracting it from the vessel which contained the blue solution. It was
effected by this wire; and surely we may say, if the battery has such
power with a metallic solution which we made and unmade, may we not find
that it is possible to split asunder the component parts of the water, and
put them into this place and that place? Suppose I take the poles the
metallic ends of this battery and see what will happen with the water in
this apparatus (fig. 20), where we have separated the two ends far apart.
[Illustration: Fig. 20.]
I place one here (at A), and the other there (at B), and I have little
shelves with holes which I can put upon each pole, and so arrange them
that whatever escapes from the two ends of the battery will appear as
separate gases; for you saw that the water did not become vaporous, but
gaseous. The wires are now in perfect and proper connection with the
vessel containing the water; and you see the bubbles rising: let us
collect these bubbles and see what they are. Here is a glass cylinder (O);
I fill it with water and put it over one end (A) of the pile; and I will
take another (H) and put it over the other end (B) of the pile. And so now
we have a double apparatus, with both places delivering gas. Both these
jars will fill with gas. There they go, that to the right (H) filling very
rapidly; the one to the left (O) filling not so rapidly; and though I have
allowed some bubbles to escape, yet still the action is going on pretty
regularly; and were it not that one is rather smaller than the other, you
would see that I should have twice as much in this (H) as I have in that
(O). Both these gases are colourless; they stand over the water without
condensing; they are alike in all things I mean in all _apparent_ things;
and we have here an opportunity of examining these bodies and ascertaining
what they are. Their bulk is large, and we can easily apply experiments to
them. I will take this jar (H) first, and will ask you to be prepared to
recognise hydrogen.
Think of all its qualities the light gas which stood well in inverted
vessels, burning with a pale flame at the mouth of the jar and see
whether this gas does not satisfy all these conditions. If it be hydrogen,
it will remain here while I hold this jar inverted. [A light was then
applied, when the hydrogen burnt] What is there now in the other jar? You
know that the two together made an explosive mixture. But what can this
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