THE AERIAL OCEAN IN WHICH WE LIVE. 53 
a small piece of phosphorus upon it. You will see that 
by putting the bell-jar over the water, I have shut 
in a certain quantity of air, and my object now is to 
use up the oxygen 
f., . . , Fig. 10. 
out of this air and 
leave only nitro- 
gen behind. To 
do this I must 
light the piece of 
phosphorus, for 
you will remem- 
ber it is in burn- 
ing that oxygen Phosphorus burning under a bell-jar (Roscoe). 
is used up. I will 
take the cork out, light the phosphorus, and cork up 
the jar again. See ! as the phosphorus burns white 
fumes fill the jar. These fumes are phosphoric acid, 
which is a substance made of phosphorus and oxygen. 
Our fairy force " chemical attraction " has been at 
work here, joining the phosphorus and the oxygen of 
the air together. 
Now, phosphoric acid melts in water just as sugar 
does, and in a few minutes these fumes will disappear. 
They are beginning to melt already, and the water 
from the pan is rising up in the bell-jar. Why is this? 
Consider for a moment what we have done. First, the 
jar was full of air, that is, of mixed oxygen and 
nitrogen ; then the phosphorus used up the oxygen, 
making white fumes ; afterwards, the water sucked up 
these fumes ; and so, in the jar now nitrogen is the only 
gas left, and the water has risen up to fill all the rest 
of the space that was once taken up with the oxygen. 
