i88o.] 
On Water and Air . 
187 
molecules of water and a redu&ion of the water to its con- 
stituent parts. I could decompose water and reduce it to 
its constituent elements in another way, — by electricity, — 
but in this case it is simply done by heat. 
Now I want to show you the decomposition of water in 
another way. I have here an apparatus (Fig. 20) by means 
of which I can send an elearic current through the water, 
and cause it to be resolved into its constituents oxygen and 
hydrogen. In the glass vessel D are two platinum plates, 
which are completely surrounded by water. The upper part 
of the glass vessel is contracted into a narrow tube, s, which 
is bent over, and the end immersed in a solution of soap- 
suds contained in a basin. Here is one end, or, as we call 
it, one pole of a voltaic battery ; and here is the other pole. 
If we now connect this battery to the platinum plates con- 
tained in the vessel D, we immediately obtain a stream of 
gas rising from the plates, and passing over through the tube 
s, collect in bubbles on the surface of the solution of soap- 
suds. 
We will take some of these bubbles on the hand, and see 
whether they do not contain a mixture of oxygen and hy- 
drogen. After a short time all the air that was in the appa- 
ratus in the first instance is entirely expelled, and we have 
nothing but the mixed gases issuing from the apparatus. [A 
few bubbles of the mixed gases having been collected on the 
solution of soap, a light was applied to them, and they ex- 
ploded with a loud detonation.] You maytake these bubbles 
on your hand and explode them without any evil effeCt 
whatever. But you have just heard the noise which accom- 
panies the combination of the oxygen and the hydrogen. 
Fig. 20. 
