UPON VEGETATION. 
301 
in respiration; while air, which is but a simple mixture of 
oxygen and nitrogen, readily parts with its oxygen in the 
act of respiration, I have made some experiments to ascer- 
tain the influence of the protoxide of nitrogen on vegetation. 
The gas which I employed was obtained by heating per- 
fectly pure nitrate of ammonia. I placed some seeds of 
cress, scattered over a moistened sponge, in a white glass 
flask, filled with protoxide of nitrogen. The seeds were 
introduced into the flask under water, and all atmospheric 
air removed as much as possible from the pores of the sponge 
by gently pressing it. A sufficient quantity of water was 
left in the flask to produce germination; the vessel was then 
closed hermetically. 
For the sake of comparison, I placed in a flask filled with 
air another sponge covered with seeds of cress. In the 
course of a few days the seeds in the last vessel were deve- 
loped, and began to form leaves. The case was different 
with the seeds in the protoxide of nitrogen; there not the 
least trace of the development of the germ could be observ 
ed; nevertheless, the seeds had swollen, and were covered 
with a mucous layer, without having experienced any other 
change which could lead to the supposition of their having 
germinated. After two weeks I removed the sponge with 
the seeds from the flask; but as soon as they were exposed 
to the air they began immediately to germinate, proving 
that during their stay in the protoxide of nitrogen they had 
not lost the power of germinating, while they do not germi- 
nate when they have been in contact for some time with 
several other gases. 
The gas in which the seed had been kept for two weeks 
had experienced no alteration; it did not contain the least 
trace of carbonic acid, and still set light to the glowing wick 
of a candle. 
To ascertain the influence of this gas on plants already 
developed, I introduced into a flask filled with protoxide of 
nitrogen a sponge covered with plants of cress perfectly 
VOL. XII. — NO. iv. 27 
