Los Angeles herald., 1907-01-27

ally used up and no longer exist as light.
II the glass il thin and of pale tint, these
varieties of light are not entirely destroyed,
but, only, weakened, and show family on the
wall if the prism is used.
The light, then, which comes from a piece
of colored glass or the gelatne screen of the
man in the theatre, is mixture of those
parts of the white sunlight or limelght
which have not been absorbed by the glass.
If this light reaches the eye and causes the
sensation of red, we call the glass or gela-
tine red.
The colors of other' objects are produced
in a similar way. Light falls upon a piece
of silk, for instance, penetrates little way
eye.
In passing through the silk, both going
and coming, some kinds of light have been
gradually destroyed, and what reaches the
eye is the mixture of what is left. This mix.
ture has certain effect upon the eye, and
we say that the color of the silk is particu-
lar shade of red.
Another piece absorbe a little more of one
kind of light and a little less of another,
and we call it different shade of red.
Other objects absorb quite different parts
of the light and have little effect on those
absorbed by the red silks, and these objects
are said to be green, blue and yellow.
If the coored object is transparent, like
glass, some of the light comes back, as in the
case of the silks, and some passes through
and appears on the other side, but both ,Por-
tions are colored, because part of the light
has been absorbed and only certain colors
| are left.
Thus a piece of blue glass appears blue,
whether looked at as it hes on a table, with
the sunlight falling upon it, or held up to the
windoy and looked through toward the sun.
few substances appear to be OF differ
ent colors when examined in these two ways,
because the effect which they have on iigh,
is different according it passes through
their whole thickness, or merely goes in lit
| tie way and comes back.
| body which absorbs all kinds of light
equally is called gray. White light falling
on such body, comes back as white light
but with diminished intensity.
| A very light gray body Is commonly called
white, and a. very dark gray body black
Strictly speaking, white object would be
ject one which absorbs all the light which
falls upon it. No such bodies exist.
| So far, we have supposed that the light
used is white, like sunlight But some
curious effects are produced by throwing
| colored Lights on colored bodies.
For instance, if room containing variou:
bright colors on the walls and furniture j:
lighted by a sunbeam which has been 'fl
tered through red glass, and all other lgh
is kept out, all objects will appear red o
black.
Anything that is ordinarily red now shine
out very brightly, objects which are orang
or yellow in daylight appear of a duer red
and blues and greens become very dark RET
or quite black.
If blue glass is used, the blue objects arr
very bright, and other colors become darl
blue or black.
A little salt put on the wick of a spirit
lamp gives IA pure yellow light, and in {
room SO lighted everything is black except
! those objects which are more or less yellow
in daylight.
A certain kind of glass allows only blue anc
red light to pass through it, and room illu
minated only by this light presents a strange
appearance, for certain blue and red objects
appear very bright and in their true colors
while other things are either black, or appear
dark blue, dark red OF dark purple.
The explanation of these effects is that, as
yellow body, for example, can reflect back
to the eye only yellow light, it will appear