115 
for, previous to its expulsion, this oxygen exists in 
union with carbon, and, therefore, as oxygen v it can- 
not be considered as producing the white colour in 
question. 
359. From the circumstance of carbonic acid be- 
ing decomposed, and its oxygen only expelled, when 
plants become green, M. Senebier, in conformity 
with the opinions of the day, was, at first, led to a- 
scribe this colour to the operation of phlogiston *, 
and subsequently, to the retention of carbon, which 
he supposes to be largely deposited in the parenchyme 
of the leaf f. But, granting that carbon is thus 
retained in the leaf, we possess no evidence that it 
is able to produce the green colour. The juice which 
communicates this colour is contained in the cells of 
the parenchyme. It is of a resinous nature, and so- 
luble in alcohol, to which it imparts its green hue : 
and this green solution possesses the same properties, 
and exhibits the same changes, from whatever leaves 
it is obtained. If a phial, about one-third filled with 
this solution, be exposed to the direct light of the 
sun, its green colour is discharged in about twenty 
minutes, and the liquor resumes nearly the transpa- 
rency of alcohol, except that it is a little tinged by 
the vegetable matter, while a yellowish precipitate is 
at the same time thrown down J. In what manner, 
then, is this discharge of the green colour produced ? 
* Mem. Plus. Chim. passim, 
t Pbys. Veg. t. iii. p. 158. 
J Mem. Phys. Chim. t. iii. p.t>. 
H 2 
