The daily exchange. [volume] (Baltimore, Md.) 1858-1861, 1858-11-19

Sun ENGRAvING.-No science within the last few
years has made so rapid progress the science of
photography; and brilliant have been its former
marvels, they are surpassed by more striking sue
cesses achieved within the month. Sun pictures on
silver and paper have been made almost as common
newspapers in every household, even the poorest;
portraits, which otherwise would have been beyond
their means, and which, hundred wears ago, regal
opulence could hardly secure. This was 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 obtaining. Petzval
pressed the most subtle mathematical analyses into
the service of the art to make its pictures ac-
curate in drawing, and more rapid in execution.
M. Niepce then showed how the sun could be made
to do the work of photographer. He covers lith-
ographic stone with solution of btumen 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 portions on which the light
has acted being soluble and the other portions inso
luble. The stone is removed from the bath and
delicate picture is found sketched on it by the in
soluble portions of btumen, from which Autographs
may be directly printed.
Our columns have related, from time to time the
various improvements of this sun-pcturing art
especially in its relation to astronomy, where i'm
provements have been as remarkable as in any other
of its numerous branches. Our advertising col
umns have shown that photography was successfully
applied not only to lithography but also to wood
engraving, and that with the greatest success
All these Impressions, however, of little
durability and permanence, compared with those
on copper. From the London Netcs, we learn
that Herr Pretsch has sought to make the sun
copper-plate engraver, and has succeeded. He
finds new property Of matter strange as
that possessed by bltumen. He covers glass
with a solution of gelatne, mixed with
a solution of bichromate of potash and other chemi-
GALS and eavesit to dry in the dark On this plate
he places his glass or paper picture which he wishes
to engrave, and exposed it to the light A faint
Photographic picture appears the prepared gela-
tinous surface. This is dipped in water. The mois-
ture 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 g1tta
percha. This gutta percha impression has but to
be covered with black lead or bronze powder, and
placed in volatile circuit, to be covered with cop
per the electrotype process-itsef wonder of
wonders. The copper plate thus produced is in re-
lief, but being placed in the matrx in the gavanic
bath, 1t produces as many engraved copper plates
as the engraver may require.
Fox Talbot the father of English photography,
goes a step beyond this. He places Herr Pretschs
solution of gelatine and bichromate of potash di-
Tectly plate of polished steel. The picture is
impressed on this film as before. He discovers that
there is no necessity to peril its faintest lines by
immersion in the water-bath. Over the faint pho
tograph the gelatnous film he sifts thin layer
of powdered gum copal, rosin. The plate
is then heated over a spirit lamp, to melt the gum
as in the common etching process. A solution of
the peroxide of iron in muratic acid is poured
the place. which eches out its surface wherever the
light has acted on the gelatine. And thus light
leaves its delicate footprints on mperishable Steel
The engraver of the highest order, who is an ar
tist well as a manipulation, may still produce the
best efforts of his art, but instead of having for
his audience only the favored few, he may be ad-
mired by the million as well The cartoons of the
great masters, which fill choice inches in the royal
galleries and grand cathedrals, the stauary which
the pilgrims of the world go far to see, the
terpieces in plastic and pictorial art, with all the
wonders of nature and science visible to the micro
scopist or the astronomer, may thus at no distant
day come to adorn the cottages of the poor