THE SPRIG OF MINT. 81 
mint into it, and stopping it up close expose 
it to the sunshine for a certain time. May we 
expect any change in the air contained in the 
jar? Whether we expect it or not, a great 
change will certainly take place. After the 
lapse of a few days we shall find that, whereas 
the air of the jar previously would have instantly 
extinguished a burning taper, now the taper ac- 
tually burns more brightly in the jar than in the 
open air. And if we were sufficiently expert in 
practical chemistry, we should detect the very 
curious fact, that all the carbonic-acid gas had 
disappeared, that in its place was an equal 
amount of oxygen gas; and, in addition, that 
the plant had increased in weight. We are 
thus plainly taught that plants can decompose 
the carbonic acid of air, and give back its two 
parts of oxygen gas, keeping its carbon, which 
they turn into solid wood, and thus increase 
in weight. 
This sprig of herb is a type of what takes 
place on the large scale all through the vege- 
table creation: the mightiest monarch of the 
ancient woods can do no more, and owes all 
its majesty of form and gigantic proportions 
G 
