172 
DR. DAUBENY ON THE ACTION OF LIGHT UPON PLANTS, 
Experiment 13. — 
Continued. 
Date. 
Circumstances of the experiment. 
Proportion 
per cent, of 
carbonic acid 
added. 
Absorption 
per cent, 
caused by 
solution of 
potash. 
Residuum 
per cent, 
afterburning 
phosphorus 
in a portion 
of the air. 
Allowance 
for phospho- 
rus vapour. 
Calculated amount 
per cent, of 
nitrogen. 
oxygen. 
July 1. 
5 P.M 
0 
5-0 
82-5 
2 
80-5 
19-5 
July 2. 
1 r. m 
0 
5-0 
79-5 
2 
77-5 
22-5 
July 3. 
12 A. M 
0 
2-0 
80-75 
2 
78-75 
21-25 
July 4. 
12 A. M 
3-25 
2-25 
81-75 
2 
79-75 
20-25 
8 r.M 
5-00 
81-5 
2 
79"5 
20-50 
July 5. 
1 P.M 
2-00 
81-25 
2 
79-25 
20-75 
July 7. 
12 A. M 
1-00 
83-75 
2 
81-75 
18-25 
Observations . — Before the experiment was brought to a close, the plant had assumed an 
unhealthy appear- 
ance ; yet the length of time during which it was confined, and the smallness of the change it produced upon 
the included air, show the more languid manner in which the functions of vegetable life are 
carried on through 
the medium of the metamorphosed leaves of this tribe of plants. A similar experiment was tried with a speci- 
men of Aloe mitreeformis, in which case also 2 per cent, was added to the amount of oxygen by its presence. 
Experiment 14. 
Aug. 30. 
12 a.m. Healthy Dahlia in a pot, 
containing one full-blown flower 
and twenty leaves, were introduced 
into the jar 
7-5 
.... 
79 
21 
8 r. m. After a day, bright till 3 p.m. 
afterwards overcast 
.... 
3-0 
79-25 
2 
77-25 
22-75 
Aug. 3 1 . 
10 r. m. Bleak and boisterous weather 
throughout the day, with much rain. 
Therm. 65° 
0 
20 
77-25 
2 
75-25 
24-75 
Sept. 1 . 
Weather cold, stormy, and bleak, but 
a bright sun occasionally. Ther- 
mometer 55° at 9 a. m 
7-5 
.... 
.... 
.... 
At 10 r. m 
2-0 
78-25 
2 
76-25 
23-75 
Sept. 2. 
Fine day but cloudy : sun at intervals 
bright. Therm. 62° at 10 r. m. . . 
0 
1-0 
79-25 
2 
77-25 
22-75 
Sept. 3. 
Dull stormy day at 9 a. m 
7’5 
• . • . 
.... 
. . . . 
At 4 r. m 
4-0 
77-25 
2 
75-25 
24-75 
Sept. 4. 
Fine day at 1 p. At 
o-o 
75-50 
2 
73-50 
26-50 
Experiment suspended, though the 
plant seemed to have suffered but very 
little from its confinement. 
Experiment 15. 
Aug. 30. 
Weather reported above. Healthy 
Dahlia, with about as many leaves 
as the former one, but without any 
flower, was introduced into the jar 
at 12 a. m 
7’5 
.... 
79 
21 
8 r. m 
0 
3-75 
.... 
. . . . 
Aug.31 . 
10 A. M 
0 
375 
82-25 
2 
80-25 
20-75 
10 r. m 
0 
2-00 
82-75 
2 
80-75 
19-25 
Sept. 1. 
10 A. M 
7'5 
950 
.... 
10 r.M 
750 
78-00 
2 
76-00 
24 00 
Sept. 2. 
10 V . M 
5 00 
79-00 
2 
77-00 
23-00 
Sept. 3. 
4 P. M 
4-00 
78-25 
2 
76-25 
23-75 
Sept. 4. 
1 P. M 
1-00 
78-00 
2 
76-00 
24-00 
Experiment was here suspended, as 
I was on the point of leaving home. 
Observations . — These two last experiments show that even plants which are in flower may purify the atmo- 
sphere, the influence of the accompanying leaves more than counterbalancing that of the parts of fructifica- 
tion : and, indeed, a comparison of the results of the first experiment with those of the second seems to indicate, 
that the presence or absence of flower does not make so great a difference as might have been anticipated. 
