The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1903-07-11
POINTS ABOUT PIGMENTS.

imparts color to an object, as does
paint. White light is made up ol
waves of different lengths, which,
when falling upon our eyes, gives us
the sensations of red, blue, green and
so forth, according to the length OF
the waves. When all the different
waves reach our eyes together, then
we see white. A pigment absorbs or
stops some of these waves of light
and reflects Others Thus if it is a
red pigment, it absorbs blue, yellow,
green and violet and reflects red. If
it is yellow pigment, it reflects yell
low only. All bright colors are not
due to pigments for instance, there
is no pigment in the rainbow. The
colors of the rainbow are due to the
fact that waves of sunlight are re-
fiected from the round raindrops at
different angles, according to their
length, and SO the white light is split
UP into the different colors of which
it is composed. The same is true of
glass prism.
The colors of flowers and leaves are
due to pigmenrs so also the colors
of most birds and butterflies, though
sometimes feathers and butterfly
scales are so constructed as to reflect
the light at different angles in the
manner of prism. These prismatic
effects in birds and butterflies may
be known from those due to pig
ments by the facts that the colors
change according to the angle at
which the objects are viewed. One
of the commonest kinds of flower
pigments is that which is either pink
or blue and is called anthocyan,
which is to say flower blue. This
sort of pigment is seen in many wild
and garden flowers, and also in some
leaves, as those of cultivated coleus.
1t is pink when the sap is acid, blue
when it is not acid or alkaline. In
some flowers, such as the for-get-me-
not, the sap of the buds is acid, and
they are accordingly pink, but later
it loses its acidity, and they become
blue. If you take some blue flower
and soak it in dilute acid, it will
shortly become pink.
Another group of pigments varies
from scarlet through orange to yell
low. These are such as color the
rays of sunfowers and the red and
yellow autumn leaves. The yellow
form which colors leaves is called
xanthophyll, which means leaf yell
low.
The green color of leaves is due to
still another pigment, called chloro-
phyll or leaf green. The substance
is of great Importance to the plant
for other reasons than that of its
color.
White pigment are sometimes found
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Flowers are made up of innumerable
little cells, and in white flowers these
are filled with air. The little parti-
cles of air reflect all the light, and so
the flowers appear white. You can
prove this by violently squeezing or
the petals of a white flower,
when they will become translucent.
The same is true of snow, which is
white because of the innumerable par
ticles of air entangled between the ice
CRYSTALS. If snow is crushed or beat
en- down, it loses its dazzling bright
ness entirely.
If you have no snow you can see
the same thing in piece of cube su-
gar. 1t is very white, but drop it
into your tea and it at once loses its
pure whiteness, while little bubbles
of air rise to the surface of the tea.
A very important animal pigment
is hamoglobin this is found in our
blood corpuscles, and gives the blood
its beautiful scarlet color. In small
quantities it looks straw yellow, so
that red blood corpuscles seen under
the microscope do not look red at all.
The hamoglobin, like the anthocy-
ans, has two different phases. When
it contains oxygen absorbed from the
air in the lungs it is bright scarlet
but as the blood travels round the
body this oxygen if set free, and the
hamoglobin thus becomes reddish
purple, as it is in our veins. You
can see the blush or purple veins at
your wrist, and you know very well
the color of scarlet blood as it flows
from a wound.