229 
to grow, and the water to rise ; but on the fourth 
day, two black spots appeared on one of the leaves, 
which gradually spread, and a fine mould began to 
form. At the end of the sixth day, two of the leaves 
had become black, and the rest, though green, looked 
sickly ; the slaked lime had now become nearly dry, 
but the jar was still dimmed by moisture ;' the plant 
had grown in all about an inch in height. Hence, 
by the gradual rise of the water, it appears, that the 
lime, as in the former case, attracted the carbonic 
acid which the plant formed ; but the dimness of 
the sides of the jar shewed the continued presence of 
moisture in the air. The chemical changes which 
the air had undergone were the same nearly in both 
cases ; and, therefore, the difference in appearance 
which the plants exhibited can be ascribed only to a 
different state with regard to the moisture, both of 
the atmosphere and of the plant. Whether the 
sickly state of the vegetable, towards the close of the 
experiment, is to be ascribed to the deleterious ac- 
tion of the lime, or to the stagnation of its fluids, in 
consequence of its confined situation, we do not un- 
dertake to say ; but there is no reason to think that 
the air had experienced any chemical change, suffi- 
cient to account for the decay and decomposition 
which had evidently begun to take place. 
511. In order to prove, that, in his experiments, 
the lime did not affect the plants from any operation 
peculiar to it, but that of abstracting carbonic acid, 
M. de Saussure states, that he sometimes employed 
potassa ; but as he has not given the details of any 
experiment made with this substance, we are unable 
