303 
Nutrition of Vegetables . 
vered with black spots, and on the fourth, the fifth, or at latest 
the sixth, they were entirely black. The effects were the same 
when the jar rested on pieces of cork on a table. Other plants 
lived a long time under similar circumstances except the pre- 
sence of mercury. 
Sennebier and Hubert too have shown, that the vapour of sul- 
phuric ether prevents germination from taking place, without al- 
tering the quantity of the air. Camphor, oil of turpentine, assa- 
fetida, vinegar, ammonia, bodies in a state of putrefaction, &c., 
have the same effect. Hence we may infer, that all those mat- 
ters, which are injurious to animals, sensibly affect vegetables 
likewise. 
We cannot therefore lay much stress on Saussure’s experi- 
ments to show the utility of carbonic acid in vegetation, particu- 
larly when we recollect an experiment of Priestley’s, which 
proved that an atmosphere with an eighth part of carbonic acid 
was sufficient to kill two plants of mint, though this small quanti- 
ty of acid was in contact with a large surface of water. 
Having found by experiment, that seeds germinate very well 
in oxydes of lead, which are known to be greedy of carbonic acid, 
I conceived, that these might contribute to elucidate the question 
respecting the utility of carbonic acid in vegetation. In conse- 
quence I moistened with distilled water some recently prepared 
oxyde of lead in the first stage of oxydation. This mixture I in- 
troduced speedily into a flint glass bottle : and though the disa- 
greeable and as it were alkaline smell that arose from it, led me 
to doubt the success of my experiment, I sowed some mustard 
seed in this oxyde, and corked the bottle tight. As I foresaw, no 
germination took place i but what I was far from expecting, and 
to my great surprise, part of the oxyde of lead in the water was 
reduced by the seeds, each of which was enveloped by a shining 
coat of metallic lead. This appeared to me to be very probably 
owing to a production of water by the union of the oxygen of 
the oxyde with the large quantity of hydrogen, that is condens- 
ed in this oily seed, which after the reduction was more or less 
carbonized. 
If the oxyd of lead be left exposed to the air for some time af- 
ter it is made, and then put into a bottle with water and seeds, no 
reduction of the metal will be effected, but germination will take 
place. 
[To be Continued ) 
