512 
On the Food of Plants. 
of common air mixed with a certain pro])ortion of carbonic acid. 
Into this vessel seven plants of Vincn minor, about eight inches 
in height, were introduced, and the whole was exjiosed to the 
sunshine for six hours during seven consecutive days ; on the 
seventh day the plants were withdrawn in a healthy state and the 
air examined, when the carbonic acid was found to have disap- 
peared, while in its place oxygen had been disengaged. The 
following are the details of the experiment : — 
Contents of jav — 
Heforo Expeihncnl. After Exiierimenf. 
Cubic inches. Cubic inclies. 
Nitrogen 211 '92 218-95 
Oxygen 56-33 71-05 
Carbonic acid .... 21-75 O'O 
Hence- 
290-0 290-0 
Cubic inches. 
Gain of oxygen 14-72 
„ nitrogen . . . , 7*03 
Oxygen assimilated . . . . 7-03 
2. Experiment repeated in the same manner on a plant of 
Lythruin salicaria. Seven days' exposure sufficed for the re- 
moval of all the carbonic acid: — 
Contents of jar — 
Before Experiment. After Experiment. 
Cubic inches. Cubic inches. 
Nitrogen 53-33 53-83 
Oxygen 14-17 20*67 
Carbonic acid .... 7-5 O'O 
Hence- 
75-0 74-5 
Cubic inches. 
Gain of oxygen 6*5 
, , nitrogen . . , . . 0*5 
Oxygen assimilated . . . . I'D 
3. Plant of Pmus Genevensis, nine inches high, exposed 
eighteen days : — 
Contents of jar — 
Before Experiment. After Experiment. 
Cubic inches. Cubic inches. 
Nitrogen 205-72 206-75 
Oxygen 54-68 67-08 
Carbonic acid .... 19-6 4-17 
280-0 
278-0 
