52 THE FAIRY-LAND OF SCIENCE. 
gasp and die just as fishes do when pulled out of the 
water. 
He would also observe very curious things going 
on in our air-ocean ; he would see large streams 
and currents of air, which we call winds, and which 
would appear to him as ocean-currents do to us, while 
near down to the earth he would see thick mists 
forming and then disappearing again, and these would 
be our clouds. From them he would see rain, hail 
and snow falling to the earth, and from time to time 
bright flashes would shoot across the air-ocean, which 
would be our lightning. Nay even the brilliant 
rainbow, the northern aurora borealis, and the falling 
stars, which seem to us so high up in space, would be 
seen by him near to our earth, and all within the aerial 
ocean. 
But as we know of no such being living in space, 
who can tell us what takes place in our invisible air, 
and we cannot see it ourselves, we must try by ex- 
periments to see it with our imagination, though we 
cannot with our eyes. 
First, then, can we discover what air is ? At one 
time it was thought that it was a simple gas and could 
not be separated into more than one kind. But we are 
now going to make an experiment by which it has 
been shown that air is made of two gases mingled 
together, and that one of these gases, called oxygen, is 
used up when anything burns, while the other nitrogen 
is not used, and only serves to dilute the minute 
atoms of oxygen. I have here a glass bell-jar, with a 
cork fixed tightly in the neck, and I place the jar over 
a pan of water, while on the water floats a plate with 
