435 
the Effect of Formaldehyde on Living Plants. 
unsuitable for the present experiments, as formic acid would be even more 
readily absorbed by the potash bulb used to absorb carbon dioxide than 
the aldehyde itself. The other depends on its absorption by ammonia to 
form formamide. Ammonia itself was too volatile for convenient use in the 
present experiments, so a modification of the method was used and aniline 
was chosen as the absorbent for formaldehyde. This works fairly efficiently, 
but the great drawback to its use was the difficulty of reabsorbing the aniline 
vapour carried away by the air-current. 
The first absorbent used was fused calcium chloride, but this did not 
absorb the vapour quantitatively. 
The second absorbent was calcium chloride and then concentrated 
sulphuric acid, but the sulphuric acid dried the air so much more efficiently 
than calcium chloride that the potash bulbs lost water, and their change in 
weight gave no measure of the carbon dioxide absorbed by them. 
The results show one or two interesting points, however, and so they 
are recorded here. 
Expt. i. Source of CH 2 0 
Absorbents 
Expt. 2. Source of CH 2 0 
Absorbents 
Expt. 3. Source of CH 2 0 
Absorbents 
Residts : — 
Formalin solution. 
Aniline, then CaCl 2 . 
Paraform. 
Aniline, then CaCl 2 . 
Paraform. 
Aniline, then CaCl 2 , thenH 2 S0 4 . 
Expt . 1. 
Expt . 2. 
Expt . 3. 
+ CH 2 0 . 
- CH 2 0 . 
+ ch 2 o . 
- ch 2 o . 
+ ch 2 o . 
- ch 2 o . 
Loss in dry wt. 
Gain on hyd. . . 
Total loss in resp. 
Gain of KOH bulb 
C 0 2 calculated . 
grm . 
0-0188 
0-0223 
0-041 1 
+ 0-0770 
0-0603 
grm . 
0-0304 
0-0223 
0-0527 
0-0000 
0-0774 
grm . 
0-0131 
0-0225 
0-0356 
+ 0-0927 
0-0524 
grm . 
0-0108 
0-0223 
0-0331 
+ 0-0652 
0-0484 
grm . 
0-0193 
0-0223 
0-0416 
+ 0-0023 
0-0612 
grm . 
0-0231 
0-0223 
0-0454 
— 0-0105 
0-0576 
These results serve to show the inadequacy of the chemical methods of 
absorbing formaldehyde. In Experiment 1 the water solution of form- 
aldehyde, after the culture without formaldehyde, absorbed the whole of the 
carbon dioxide as well as the aniline. In Experiment 3 the sulphuric acid 
used to absorb aniline caused a loss of water from the potash bulbs. In 
Experiment 2 the whole of the aniline was not absorbed. But, as a slight 
increase in the weight of carbon dioxide was shown by the formaldehyde 
culture in all these experiments, it was thought probable from these results 
that formaldehyde was used as a source of carbon dioxide ; but as the 
amount of aniline passing through would depend on the speed of the air- 
current, which was hard to regulate uniformly, no real conclusion of any 
kind can be drawn from the experiments. 
