5G Dr. D. P. Gardner onthe, 
ficient gas each for three analyses, the mean of which gave, nix 
trogen 96:2, oxygen 3-8, without carbonic acid. aA: * 
air at the same time yielded 20°8 per cent. oxygen. e 
_ The grass. plants B yield gas, but usually in such small. asin 
ties as to be unserviceable, but two examinations obtained gave, 
nitrogen 96-0, oxyn 4:0, without.carbonic acid. P 
21. The two Datura plants C, with only their leaves Thales 
ated, were exposed at the window on the evening of the 26th, — 
and furnished sufficient gas at 11 o’clock the next morning for 
six analyses; the gas in both was similar, cneek an “ a 
nitrogen 96'5, oxygen 3-5 per cent., without carbonic acid. Ss 
» RR Neither the grasses not Datuiras furnished any gas in cont “ 
plete darkness, although the experiments were continued until 
the specimens were decomposed. We see however that an ex- 
posure to darkness for thirty-six as ane not arrest the nea 
action of Datura in section 20. — ye 
~ 23. Deductions.—The foregoing’ sa eel pean that: the as 
icles roots of plants, so far as these specimens are concerned, i | 
appear to evolve’ gas, but in different amounts, and that the gas 
consists of nearly pure nitrogen and is very abiform é in compo> 
sition under the same circumstances... The exposure of roots to 
light or darkness does not seem to influence the result, but the ae 
action of. light | on the leaves is essential to the production of gas. ne 
24. The gas collected in the reservoir was in some Piwwaco dee 
rived from the sides of the glass and did not appear to be emitted _ 
from the root, but was collected in minute bubbles over its fibres. 
The evolution did not however depend upon the mechanical ac- 
- tion of light or heat, for the water in the darkened vessels and _ 
some placed for comparison without any plant did not furnish any. — 
The composition of the gas is also opposed to this supposition, — 
for by Prof. Morren’s researches, (Ann. de Chim, &c., Sept. 
1844, ) it is shown that the sun’s light liberates carbonic acid and — 
nitrogen, accumulating oxygen in the water, a reoult very differ- 
ent from what occurred in these cases. : ] 
. The gas contained in pump-water and separated by- boiling, i 
was nitrogen 48-0, oxygen 22-0, carbonic acid 30-0. per cent. 
The root acting on this mixture disturbed its composition by ab- 
sorbing the carbonic acid and most of the oxygen present, i 
canine water Sobendon the nittopen for whit it Bae bat | 
feeble af ‘Therefore w | | 
