209 
ried on from, August 6th, till August 14th, 
1807 > during this time, though the weather had 
been generally clouded, and there had been 
some rain, the volume of elastic fluid continued 
to increase. Its quality was examined on the 
morning of the 15th ; it contained of carbonic 
acid gas, and 100 parts of it afforded 23.5 of 
oxygene gas. 
These facts confirm the popular opinion, that 
when the leaves of vegetables perform their healthy 
functions, they tend to purify the atmosphere in 
the common variations of weather, and changes 
from light to darkness. 
In germination, and at the time of the decay of 
the leaf, oxygene must be absorbed ; but when it 
is considered how large a part of the surface of the 
earth is clothed with perennial grasses, and that 
half of the globe is always exposed to the solar 
light, it appears by far the most probable opinion, 
that more oxygene is produced than consumed 
during the process of vegetation ; and that it is 
this circumstance which is the principal cause 
of the uniformity of the constitution of the at- 
mosphere. 
Animals produce no oxygene gas during the 
exercise of any of their functions, and they are 
constantly consuming it ; but the extent of the ani- 
mal, compared to that of the vegetable kingdom 
is very small ; and the quantity of carbonic acid 
gas produced in respiration, and in various processes 
of combustion and fermentation, bears a proportion 
extremely minute to the whole volume of the at- 
mosphere : if every plant during the progress of its 
p 
