es out is steam or not. I think you will soon see
the jar (F) will be filled with vapour, if that which rises from the water
is steam. But can it be steam? Why, certainly not; because there it
remains, you see, unchanged. There it is standing over the water, and it
cannot therefore be steam, but must be a permanent gas of some sort What
is it? Is it hydrogen? Is it anything else? Well, we will examine it. If
it is hydrogen, it will burn. [The Lecturer then ignited a portion of the
gas collected, which burnt with an explosion.]

[Illustration: Fig. 19]

It is certainly something combustible, but not combustible in the way that
hydrogen is. Hydrogen would not have given you that noise; but the colour
of that light, when the thing did burn, was like that of hydrogen: it
will, however, burn without contact with the air. That is why I have
chosen this other form of apparatus, for the purpose of pointing out to
you what are the particular circumstances of this experiment. In place of
an open vessel I have taken one that is closed (our battery is so
beautifully active that we are even boiling the mercury, and getting all
things right--not wrong, but vigorously right); and I am going to shew you
that that gas, whatever it may be, can burn without air, and in that
respect differs from a candle, which cannot burn without the air. And our
manner of doing this is as follows:--I have here a glass vessel (G) which
is fitted with two platinum-wires (IK), through which I can apply
electricity; and we can put the vessel on the air-pump and exhaust the
air, and when we have taken the air out we can bring it here and fasten it
on to this jar (F), and let into the vessel that gas which was formed by
the action of the voltaic battery upon the water, and which we have
produced by changing the water into it,--for I may go as far as this, and
say we have really, by that experiment, changed the water into that gas.
We have not only altered its condition, but we have changed it really and
truly into that gaseous substance, and all the water is there which was
decomposed by the experiment. As I screw this vessel (GH) on here (H), and
make the tubes well connected, and when I open the stop-cocks (HHH), if
you watch the level of the water (in F), you will see that the gas will
rise. I will now close the stop-cocks, as I have drawn up as much as the
vessel can hold, and being safely conveyed into that chamber, I will pass
into it an electric spark