217 
obtained from the bark and from the alburnum ; 
the first of which contains more carbonaceous mat- 
ter than the last. 
When the similarity of the elements of different 
vegetable products is considered according to the 
views given in the Third Lecture, it is easy to con- 
ceive how the different organized parts may be 
formed from the same sap, according to the man- 
ner in which it is acted on by heat, light, and air. 
By the abstraction of oxygene, the different in- 
flammable products, fixed and volatile oils, resins, 
camphor, woody fibre, &c. may be produced from 
saccharine or mucilaginous fluids; and by the 
abstraction of carbon and hydrogene, starch, sugar, 
the different vegetable acids and substances soluble 
in water, may be formed from highly combustible 
and insoluble substances. Even the limpid volatile 
oils which convey the fragrance of the flower, 
consist of different proportions of the same essential 
elements, as the dense woody fibre ; and both are 
formed by different changes in the same organs, 
from the same materials, and at the same time. 
M. Vauquelin has lately attempted to estimate 
the chemical changes taking place in vegetation, 
by analyzing some of the organized parts of the 
horse -chesnut in their different stages of growth. 
He found in the buds collected, March 7 . 1812, 
tanning principle, and albuminous matter capable 
of being obtained separately, but when obtained, 
combining with each other. In , the scales sur- 
rounding the buds, he found the tanning principle, 
a little saccharine matter, resin, and a fixed oil. 
In the leaves fully developed, he discovered the 
