The Milan exchange. (Milan, Gibson County, Tenn.) 1874-1978, 1880-01-08
USEFUL AND SCIENTIFIC.

.
PHOTOGRAPHS IN NATURAL CoLoRs
Captain Abney, the well known En-
glish photographer, has succeeded in
obtaining pictures of the solar spec
trum in It's natural colors, both on silver
plates and on compounds of silver held
in place by collOdion. The photographs
are produced by, oxidation of silver
compounds when placed In the spec
trum, the coloring matter being due APP
parently to a mixture of two different
sizes of molecules of the same chemical
composition, one Of which sbsorbs at
the blue end and the other at the red
end OF the spectrum; and the sizes Of
the molecules are unalterable while ex-
posed to the same wave-lengths as those
by which they were produced. Captain
Abney believes that the cOlors may be
preserved unchanged when exposed to
ordinary daylight. He has thus sue
ceeded in explaining the action by
which Becquerel some years ago o.
tanned photographs in coloTs as pro-
-duced by oxidation, and not due TO in
reference. Becquerel's photographs
were fugitive; Captain Abney appears
TO have succeeded in ''fxing" his An
exposure of two minutes with a vice
slit was sufficient to produce the pictures
TO the spectrum. a3t
FRENCH METHOD or FLOORING.
The improved method of laying down
floors which has been adopted in France
is, it appears, obtaining a wide apI1iica-
ton The plan consists in simply put
ting down the flooring, not, as COM
monty, on joists, but in imbedding the
boarding in asphalt-sach floors as these
being found particularly adapted, among
other examples, for the ground stories
of barracks, hospitals, churches, court
houses, etc. According TO this method,
pieces of oak, usually two and one-half
to four inches broad, twelve to thirty
inches thick, are, pressed down into
layer of hot asphalt not quite half an
inch thick in the well known herring
bone pattern. To insure a complete ad-
hesion of the wood to the asphalt, and
obtain the smallest possible joints, the
edges of the pieces of wood are planed
down beveling toward the bottom, so
that their cross sections becomes wedge
like Nails, of course, are not neces-
sary, and perfectly level surface may
be given to the flooring by planning after
the operation of laying down. Some of
the advantages of this flooring, which
only requires an even bed on which to
rest, are the, following Damp from be-
low and it's consequence, rot, are pre-
vented; floors may be cleaned quickly
and with the least amount of water, in
surfing rapid drying; vermin have no
opportunity to accumulate in the joints;
and unhealthful exhalations from the
soil can not penetrate through.
The MOTIVE PowER.-The various
matters which an animal eats consists
of pure food-stuffs and of useless con-
comitant bodies; Just as coal consists of
pure fuel and of the useless mineral mat
ter known as ash. When an animal
eats his dinner the process of digestion
and assimilation takes place, and has
the ultimate result of separating the
pure food-stuffs from the useless con-
comitants. The latter bodies are re-
jected at once, but the food-stuffs are
taken up with his veins, incorporated
with the blood (Which consists OF food
in different degrees of combustion) AID
used for building up the various portions
of his body. Surprising the animal
were mere growing object like crys-
tai, with no work to perform and no
consequent waste of material, the
process would stop here, and the erea-
ture would wax bigger and bigger from
day to day, without any alteration in
place or redistribution of assimilated
matter But the animal is essentially a
locomotive machine, and the purpose
for which he has taken in his food is
simply that he may use it up in produc-
ing motion. For while he slows it
away in his muscles, or lays it by for
future use as fat; but its ultimate desti-
nation in every instance is just as truly
TO be consumed for fuel as is the case
with the coal in the steam en-
CINE. The food, however, only
gives us one-half of the necessary
materials for the liberation of dormant
energy. Oxygen is needed to give us
the other half. This oxygen we take in
whenever we breathe. Animals ike
fishes or sea-snails obtain the necessary
supply from the water by means of gills;
for large quantities of oxygen are held
in solution by water, and the needs of
such comparatively sluggish creatures
are not very great. With them little
energy goes d long way. Air-breath-
ing animals ike ourselves, on the other
hand, need relatively large quantities of
the energy-giving gas in order to keep
up the constant movements and high
temperature of their bodies. Such crea-
lures accordingly take in the oxygen by
great inhalation, and absorb it in their
lungs, where it passes through the thin
membrane of the capillaries, or very
tiny blood vessels, and so mixes freely
with the blood itself. Thus we have
food, supplied to the blood by the stom-
ach, the exact analogue of the coal in
the engine; and oxygen supplied to the
blood by the lungs, the exact ana
laguo Of the draft in the engine. When
ever these two substances-the hydro
carbonaceous foods and the free oxygen
--reunite, they will necessarily give out
heat and set up active movements
Belgrgyia. -"