225 
lime, irt the former experiment, was found to be sa- 
turated with carbonic acid ; and since, in these ex- 
periments, the atmospheres still contained a consider- 
able portion of oxygen, it is concluded, that the fall 
of the leaves was not owing to the want of that gas$ 
but to the absence of carbonic acid alone *. 
506. It may be remarked, that, in these last ex- 
perimentS) the effects produced on the plants are very 
different from those before related, as is also the time 
required for their completion ; for, in the first experi- 
ments (5CXX), the leaves soon became yellow, and in 
a few days fell off; while in the second, they continued 
green, became dry, and did not fall entirely till the 
end of the third week. Now, it is very doubtful 
whether the mere abstraction of carbonic acid would 
occasion either the one or the other of these states 
of the leaves ; and it is in no respect probable that 
it should produce them both. In fact, the results of 
these two series of experiments correspond with those 
which we have related (43.) on a former occasion ; 
and although M. de Saussure states, that, in the lat- 
ter series, he previously moistened the lime, yet he 
did it only slightly ; and as evaporation from the 
leaves was soon checked by their confined situation, 
they could not have become dry, but from the at- 
traction of their moisture by the lime. While, 
therefore, the effects on the plants were probably 
produced, in the first experiments, by the vaporization 
of the lime, it appears to us almost certain, that, in the 
last examples, they arose from the abstraction of 
Recherches, p, 38. 9. 
