Mr. Hunt describes a process, discovered by himself by which the
Daguerrean art may be applied to paper. His description is as
follows:--
"Placing the paper on some hard body, wash it over on one side--by
means of a very soft camel's hair pencil--with a solution of sixty
grains of bromide of potassium, in two fluid ounces of distilled water,
and then dry it quickly by the fire. Being dry, it is again washed
over with the same solution, and dried as before. A solution of
nitrate of silver--one hundred grains to an ounce of distilled
water--is to be applied over the same surface, and the paper quickly
dried in the dark. In this state the papers may be kept for use.
"When they are required, the above solution of silver is to be
plentifully applied, and the paper placed wet in the camera, the
greatest care being taken that no day light--not even the faintest
gleam--falls upon it until the moment when you are prepared, by
removing the dark slide, to permit the light, radiating from the object
you wish to copy, to act in producing the picture. After a few seconds
the light must be again shut off, and the camera removed into a dark
room." The necessity of removing the camera is now avoided by the use
of the dark slide, already described, covering the picture in the
holder, which alone may be removed.--Amer. Aut.
"It will be found by taking the paper from the holder, that there is
but a very faint outline--if any--yet visible. Place it aside, in
perfect darkness until quite dry; then place it in the mercurial vapor
box (meaning bath) and apply a very gentle heat to the bottom. The
moment the mercury vaporizes, the picture will begin to develope
itself. The spirit lamp must now be removed for a short time, and when
the action of the mercury appears to cease, it is to be very carefully
applied again, until a well defined picture is visible. The
vaporization must then be suddenly stopped, and the photograph removed
from the box. The drawing will then be very beautiful and distinct;
but much detail is still clouded, for the developement of which it is
only necessary to place it in the dark and suffer it to remain
undisturbed for some hours. There is now an inexpressible charm about
the pictures, equaling the delicate beauty of the daguerreotype; but
being very susceptible of change, it must be viewed by the light of a
taper only. The nitrate of silver must now be removed from the paper,
by well washing it in soft water, to which a small quantity of salt has
been added, and it should afterwards be soaked in water only. When the
picture has been dried, wash it quickly over with a soft brush dipped
in a warm solution of hyposulphite of soda, and then wash it for some
time in distilled water, in order that all the hyposulphite may be
removed. The drawing is now fixed and we may use it to procure
positive copies, (the original being termed a negative,) many of which
may be taken from one original."
"The action of light on this preparation, does indeed appear to be
instantaneous. The exquisite delicacy of this preparation may be
imagined, when I state that in five seconds in the camera, I have,
during sunshine, obtained perfect pictures, and that when the sky is
overcast, one minute is quite sufficient to produce a most decided
effect."
"This very beautiful process is not without its difficulties; and the
author cannot promise that, even with the closest attention to the
above directions, annoying failures will not occur. It often happens
that some accidental circumstance--generally a projecting film or a
little dust--will occasion the mercurial vapor to act with great energy
on one part of the paper, and blacken it before the other portions are
at all effected. Again, the mercury will sometimes accumulate along
the lines made by the brush, and give a streaky appearance to the
picture, although these lines are not at all evident before the
mercurial vapor was applied. (A brush sufficiently large--and they may
be easily obtained--will, in a measure, prevent this difficulty.--Amer
Au.) I have stated that the paper should be placed wet in the camera;
the same paper may be used dry, which often is a great convenience.
When in the dry state a little longer exposure is required; and instead
of taking a picture in four or five seconds, two or three minutes are
necessary."
The durability of daguerreotypes has been, and is still, doubted by
many, but experiment has proved that they are more permanent than oil
paintings or engravings.
ETCHING DAGUERREOTYPES.--There are several methods of accomplishing
this object; discovered and applied by different individuals.
The first process was published at Vienna by Dr. Berres, and consisted
in covering the plate with the mucilage of gum arabic, and then
immersing the plate in nitric acid of different strengths.
Mr. Figeau, of whom I have already spoken, likewise discovered a
process for the engraving of Daguerreotypes; and founded on the belief
that the lights of a Daguerreotype plate consists of unaltered silver,
while the dark or shadows consists of mercury or an amalgam of mercury
with silver. He finds that a compound acid, consisting of a mixture of
nitric, nitrous, and muriatic acids, or of nitric mixed with nitrate of
potass and common salt, has the property of attaching the silver in
presence of the mercury without acting upon the latter. Bi-chloride of
copper answers the purpose also, but less completely.
"When the clean surface of a Daguerreotype plate is exposed to the
action of this menstruum, particularly if warm, the white parts, or
lights are not altered, but the dark parts are attacked, and chloride
of silver is formed, of which an insoluble coating is soon deposited,
and the action of the acid soon ceases. This coat of chloride of
silver is removed by a solution of ammonia, and then the acid applied
again, and so on, until the depth of biting in is sufficient. However,
it is not possible, by repeating this process, to get a sufficient
force of impression; a second operation is required, in order to obtain
such a depth as will hold the ink, to give a dark impression; for this
purpose the whole plate is covered with drying oil; this is cleared off
with the hand, exactly in the way a copper plate printer cleans his
plate. The oil is thus left in the sinkings, or dark bitten in parts
only. The whole plate is now placed in a suitable apparatus, and the
lights or prominent parts of the face are gilt by the electrotype
process. The whole surface is now touched with what the French
engravers call the "Resin Grain," (grain de resine), a species of
partial stopping out, and it is at once bitten in to a sufficient depth
with nitric acid, the gilding preserving the lights from all action of
the acid. The resin grain gives a surface to the corroded parts
suitable for holding the ink, and the plate is now finished and fit to
give impressions resembling aquatint. But as silver is so soft a metal
that the surface of the plate might be expected to wear rapidly, the
discoverer proposes to shield it by depositing over its whole surface a
very thin coat of copper by the electrotype process; which when worn
may be removed at pleasure down to the surface of the noble metal
beneath, and again a fresh coat of copper deposited; and so an
unlimited number of impressions obtained without injuring the plate
itself."
If, as has been asserted, steel may be rendered sufficiently sensitive,
to take photographic impressions, to what a revolution will the art of
engraving be subject by the discovery of this process.