THE LEAF 



127 



is decomposed under the influence of the leaf and oxygen 

 is given off. Consequently a fresh quantity of carbonic 

 acid dissolves and so on. This experiment proves 

 veiy clearly, though not very exactly, that in passing 



FIG. 37. 



by the leaf from one part of the tube into the other, 

 carbonic acid changes into oxygen. During this process 

 of decomposition the volume of carbonic acid which 

 disappears at one end of the tube and the volume of 

 oxygen which appears at the other end are approxi- 



