i86 
On Water and Ah. 
[March, 
in the flask F, and steam is passing over this incandescent 
spiral. The mind of every boy here present must figure the 
atoms of the spiral as vibrating in the most intense manner 
and coming into collision with the molecules of steam which 
are passing over the spiral. You must imagine that the 
vibrations of the incandescent spiral are shaking those mole- 
cules of water asunder, and are converting the water into its 
Fig. 19. 
constituent atoms of oxygen and hydrogen. You see those 
bubbles that are being carried down the tube T, and are 
rising in the tube t' and colledting in the upper part of the 
tube? These bubbles that you see rising are not bubbles ot 
steam, and they are not bubbles of air, but they are bubbles 
of the mixed gases, oxygen and hydrogen, which are the 
constituents of water. Here the gases are colletting, and 
if we allow the operation to go on for a minute or so we 
shall obtain a certain amount of gas at the upper part ot the 
tube. We can cause the two mixed gases to combine imme- 
diately, simply by sending an eledtric spark between the two 
points of platinum which are sealed into the top of the tube, 
and you see the bright flash of light produced at the moment 
of their combination. Thus, by this simple experiment, we 
obtain, mechanically speaking, a shaking asunder ol the 
