The mountain sentinel. [volume] (Ebensburg, Pa.) 1844-1853, 1852-11-18
Aut Unl nal Foliage.

| The beautiful appearance of the autumnal To-
liage, which this year seems almost to surpass
in gorgeousness that of any previous season, of
ten induces an inquiry to the reason of the
change which a few frosty nights make in the
green livery OF our trees and forests. The ques-
ton is purely chemical one, and one moreover,
about which there is very general agreement
of opinion. In fact, there is subject inclu-
ded among natural phenomena more difficult to
explain than this change in the constitution or
Arrangement of matter whereby particular
body is caused to reflect or absorb light in such
n way that it assumes at one time a wholly diff
ferent color. These changes very far from
| being confined to zny one species Of matter
! The trout, which a sandy bottom, has yel-
low, speck!ed hue, becomes dark brown or blue,
beneath shaded bank the yellow of the wea-
sci and the rabbit, maintained during the sum-
mer months is already changing to white and it
is susceptible of rigid demonstration that the
blue of the October sky is not the same, either
in tint or quality, with that which welcomed the
bursting of the leaf in the months of April and
May.
The general supposition in regard to the
change OF the leaves is this: When the tree or
plant is in full activity, its foliage, 1t is well
known, absorbs carbonic acid and disengages
oxygen. When, now, through the influence of
n sufficiently low temperature, or from any 9th
er cause, the functions of vegetable life are sus-
pended and the fluids cause TO circulate, the
leaves no longer disengage oxygen, but, in COM
mon with all dead bodies, absorb this gas, which
forming an acid, changes the colors of leaves
either to yellow, red, or some intermediate shade
depending on the quality of the matter present
in the leaves. 1t has also been asserted that
this acid can be neutralized by alkali, and
the green restored. Tlss- is not however, the
case. A leaf does not becoms green by any re-
agent; but when it has become red, solution
OF potash will change it 90 green. because the
red coloring matter forms green compounds with
that alkali.
BerEelius. the great Swedish chemist, spent
considerable t.ne IN f-rrssssxs4fnz7this subject
lie found that when tbs yeley leaves we're trea-
ted with alcohol. .ttey. re ssva'a granular sub
stance. which had a tcrfencs> To- crystaiization,
and also a yellow. soft, fatty Substance. which
appeared identical with the grains These con
tanned the How colorins matter of the leaves,
which is described yellow, fatty unctious
substance. easily melted, and on cooling becom-
ing concrete and transparent When moistened
with water, and long exposed to the air and
light, it loses its color entirely, Berzelus of
the opiuion that the transformation of the green
coloring matter of the leaf into yefl5w, is eff
ected by change in the organization of the
leaf produced by the frost. Every effort to
produce the green from the yellow proved fruit
less; neither could he stcceed in changing the
green coloring matter to yellow. The red colo
ring matter of the leaves has been also extract
ed, and is believed to be the same with that of
red fruits. The brown color which leaves
sumo when completely withered has nothing in
common with either the red or the yellow col
ors. 1t is produced by an extractTVe principle,
originally colorless but which, when the epider-
mis- or outer layer of the leaf structure has de-
cayed off, is acted upon by the oxygen of the
air. and communicates to the ferrous skeleton
of the leaf the well known brown color. This
color is one of the most fixed and Interchangeable
with which are acquainted; and cannot be
Impaired or destroyed by the most powerful
chemical reagents. This, we believe, embodies
all that is at present known, scientifically spea-
king respecting the change of the leaves. The
different appearance presented by different trees
must be referred to difference in their nature,
and the different changes observed in different
countries and locations is undoubtedly owing to
different climate condtions.-Sprinafeld Repub-
Hcdn.