Bellows Falls times. [volume] (Bellows Falls, Vt.) 1856-1965, 1860-04-06
MISCELLANY Y.
The sun an Engrayer.

No science within the last few years has
made 80 rapid progress as the science of
photography; and brilliant as have been its
former marvels, they are surpassed by more
striking successes achieved almost within
the month. Sun pictures on the silver and
paper have been made almost as common
as newspapers in every household, even the
poorest portraits, which otherwise would
have been beyond their means, and which,
a hundred years ago, regal opulence could
hardly secure. This was a great addition
to the happiness of the world for any art to
contribute. But its devotees still asked for
more; and more they succeeded in obtain
ing. Petzwal pressed the most subtle math-
ematical analysis into the service of the art,
to make its pictures more accurate in draw
ing, and more rapid in execution. Mr..
Niepec then showed how the sun could be
made to do the work Of photographer. He
covers lithographic stone with solution
of bItumen in ether; over this he places
any Photographic picture on glass or paper,
or an engraving. This is subjected to the
action of the light. The stone is then
placed in bath of ether, the portion on
which the light has acted being soluble and
the other portion insoluble. The stone is
removed from the bath and delicate pic
ture is found sketched on it by the insolua-
BILE portions of the bitumen, from which
Autographs may be printed direct.
Our columns have related from time to
time the various Improvements of this sun
picturing art, especially in its relation TO as
tronomy, where improvements have been
as remarkable as in any other of its nu-
merous branches. Our advertising col
umns have shown that photography was sue
cessively applied not only to lithography,
but also to wood engraving, and that with
the greatest success. All ltheseimpressions,
however, are of little durability and per-
manence, compared with those on copper.
/ From the London News we learn that
/ Herr Pretsch has sought'to make the sun a
copper-plate engraver, and has succeeded.
/ He finds a new property matter as strange
as that possessed by bitumen. lie covers
a glass case with solution of gelatine, mix
ed with a solution of birchromate of potash
and other chemicals and leaves it TO dry in
the dark. On this plate lie places his glass
or paper picture which he wishes TO en-
grave, and exposes it to the light. A faint
Photographic picture appears on the pre-
pared gelatinous surface. This is dipped
ia water. The moisture raises the picture
in relief. 1t is dried, and found to be
strong enough and deep enough to afford
an impression, by pressure, to warm sheet
Of gutta percha. This gutta percha i'm
preston has but TO DO covered with black
lead or bronze powder, and place in a vol
taic circuit. to be covered with copper by
the electrotype process-itself a wonder of
wonders. The copper-plate thus produced
is in relief; but being placed in the matrix
in the galyanio bath, it produces rs many
engraved copper plates as the engraver may
require.
Fox Talbot, tho Father OF English pho
Biography. goes a step beyond this. lie
places Herr Preisch's solution Of gelatine
and biclromate Of potash directly on plate
Of polished steel. The picture IS impressed
on the film as before. lie discovers that
there Is 10 necessity TO peril It's fainiesi
lines hv immersion in the water bath. Over
the faint photograph on the gelaiinOus film
he sifts a thin layer of powdered gum CO
pal, or even rosin. The plate IS then heat
ed over spirit lamp TO melt the gum, as
in the common etching process. a solution
Of the peroxide Of iron in muriate acid i