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Transcriber Note

Text emphasis is denoted as _Italics_ and =Bold=.




                     THE DRY COLLODION PROCESS.


                                 BY

                          CHARLES A. LONG.


                           THIRD EDITION.

                PUBLISHED BY BLAND & LONG, OPTICIANS,

                                 AND

           PHOTOGRAPHIC INSTRUMENT MAKERS TO HER MAJESTY,

                           [Illustration]

                           BY APPOINTMENT.

                     153, FLEET STREET, LONDON.


                    ENTERED AT STATIONERS' HALL,

                    _Price 1s. Per Post 1s. 1d._

                                1858.


  H. SILVERLOCK, PRINTER,
  WARDROBE TERRACE, DOCTORS' COMMONS, LONDON, E.C.





PREFACE TO FIRST EDITION.


The following pages shall be devoted to the description of
a process on Dry Collodion, which I believe to be at once simple and
effective. The experiments connected with the perfection of this
process have occupied my leisure time for the space of two years
or more, and have been conducted with all the care of which I was
master. The constant repetition of them enables me to say, that
whoever will follow diligently the process step by step, as detailed
in this Pamphlet, must succeed in producing pictures in every way
such as could be required by the most exacting critic.

The process is simple, clean, and expeditious; and the resulting
Negatives possess the exquisite softness of Albumen, the brilliancy
of the wet Collodion, and the fine artistic texture of the Paper
process.

To disarm criticism, and to make peace with my fellow labourers in
the art, I wish it to be understood that I do not claim the use of
Collodion, of Gelatine, of Metagelatine, or of any of the Chemicals
used in the process--most of these have been employed by others in
various ways; I merely reserve to myself the pleasure of placing
in the hands of Photographers a definite and simple plan by which
pictures may be taken on Dry Collodion.

                                                     CHARLES A. LONG.

  _June 20, 1857._




PREFACE TO SECOND EDITION.


In issuing a second edition of the Dry Collodion process,
I would take occasion to remark, that after some months' practical
working, it has not been found necessary to make any material
alteration in the process; success has usually attended the adoption
of it, and in those cases where good pictures have not resulted, the
failure has always been traced to the use of a Collodion not suited
to the process.

I cannot allow this opportunity to pass, without thanking those
gentlemen whose opinions possess weight in matters photographic, for
the very candid manner in which they have tested the capabilities of
my process, and for the very flattering testimony they have borne to
its efficiency, simplicity, and certainty.

                                                     CHARLES A. LONG.

  153, Fleet Street,

  _September 1857_.




PREFACE TO THIRD EDITION.


The process described in the following pages has now been
in use for twelve months, and I have much satisfaction in stating
that it has, in almost every instance where it has been adopted and
carried out with care and attention, yielded results which leave
scarcely anything to be desired.

The present Edition might more properly be termed a reprint, as the
alterations in the text do not extend to more than a few matters of
detail, which experience has shewn to be desirable, the principles of
the process remaining undisturbed.

                                                     CHARLES A. LONG.

  153, Fleet Street,

  _June 1858_.




OPINIONS OF THE PRESS.


_From the Athenæum._

We have not merely examined the description given by Mr. Long of his
dry collodion process, but we have witnessed the results obtained by
following carefully his directions. It appears to us that, by it, a
collodion plate may be prepared at home, wrapped in paper, and packed
in portmanteau; that we may journey to Rome or Venice, then place
our plate in the camera obscura, and allow it for a few minutes to
receive the luminous image; remove it in a dark room; re-pack it
and trouble ourselves no more about it until our return to England;
when, in the room in which it was prepared, we may witness the magic
process of development, and rejoice that we have, without much
labour, secured a picture of the Coliseum or of the Bridge of Sighs.


_From the Journal of the Cambrian Archæological Association._

New Photographic Process.--Mr. Long, of the firm of
Bland and Long, Opticians, Fleet Street, has recently put forth a
valuable pamphlet, in the form of an essay on the dry collodion
process. By means of this, plates prepared weeks beforehand may
be exposed to objects, and then kept for weeks afterwards before
they are developed, as he has proved it himself on the Continent.
The advantage of this process to travellers, and especially to
archæologists, is immense; because hitherto the main drawback upon
photography has been the trouble and expense of carrying chemicals,
tents, &c. &c., besides the camera, with its lenses, to the scene of
operation. Now, however, it will be sufficient to carry merely the
camera, with a suitable supply of plates prepared according to this
process. The observer can then, by merely exposing his plates, with
the proper precautions, _bag_ any number of views per diem, and on
his return home can develop them--or have them developed--at leisure.
If this process succeeds, it will have the effect of splitting
photography into two distinct branches--the _æsthetic_, and the
_practical_. The former will fall to the share of the intelligent
observer, the traveller, the man of taste, who will go and search
for objects, combine them, or use them, under the most favourable
æsthetic circumstances, and then will carry them home to be handed
over to the man of practice. Once in his hands, nothing will remain
but to manipulate the plates according to the rules of photographic
science, by means of all the best appliances that a well fitted
laboratory can furnish. One branch will feed the other. One will be
the department of observation, of search, of taste, of beauty; the
other will be that of calm scientific development, of improvement,
of preservation. One man will be like the artist who paints; the
other like the artist who engraves. One will be like the author, the
man who writes; the other like the printer, the man who perpetuates.
We recommend members to enquire carefully about this new process;
because if it becomes firmly established, any archæologist moving
about the Country may get views of churches, castles, cromlechs,
meini-hirion, seals, &c. &c., _usque ad satietatum_--we had almost
said _ad nauseam_; but that word can never be connected with
archæology! The upshot of this is,--"Read Mr. Long's pamphlet, and
set up a portable camera with his prepared plates, as we intend doing
ourselves!"


_From the Liverpool and Manchester Photographic Journal._

We must advise all who are interested in dry processes to obtain Mr.
Long's clearly written pamphlet. (Leader, July 15th, 1857.)


_Extract from Proceedings of Charlton Photographic Society, October
8th, 1857. Paper by Mr. Hooper,--On the results of his experience in
the practice of several Preservative Processes._

I commenced experimenting on the process of Mr. Long. The success I
have met with from the first has convinced me that that process will
ere long be generally adopted: the plates being easily and quickly
prepared, and keeping well, is a great advantage.


_Extract from Letter from G. R. Smith, Esq., to the Editor of the
London Photographic Journal, Sept 21, 1857._

My tour of a fortnight's duration having ended, I returned to London,
and began developing (the dry plates). To my great delight, I found
all Mr. Long had said in favour of his process fully realized.
Picture after picture (I took twenty-eight) came out with great
beauty, and so far as the process is concerned, I have not had a
single failure.


_Mr. Long's Dry Collodion Process._

_Letter from Robert Hunt, Esq., F.R.S., to the Editor of the London
Photographic Journal, October, 1857._

                                             6, Green's Row, Chelsea.

Sir,--It is due to Mr. Long that I should state what my experience
has been with his dry collodion plates, and I feel much satisfaction
in doing so, being enabled fully to confirm all that Mr. Smith has
said respecting the dry plates prepared as he has described (Photo.
Journ. Sept. 21). On the 26th of August, Mr. Long, at my request,
furnished me with some of his dry collodion plates. Absence from
London, and the press of official engagements, prevented my trying
any experiments with those plates until the 30th of September.
Although the weather was very unfavourable, the result was superior
to my expectations. On the 7th of October, at four in the afternoon,
when the sky was covered with clouds and the weather stormy, I
exposed a plate in the camera obscura for ten minutes to the dark
brick building, Chelsea Hospital. I enclose you a positive print from
the result of this experiment. When we remember that the sensitive
plate had been kept by me for a period of _forty-two days_, and then
exposed under very unfavourable circumstances, I think you will admit
that the result is satisfactory. I should not content myself with
this trial, but that I am again compelled to leave London for a long
period, and I shall have no other opportunity of testing these plates
for this year. I feel convinced that the traveller might with perfect
safety use plates which have been prepared for a month, and thus
relieve himself from much labour and frequent annoyance, by the use
of Mr. Long's process.

                                                         Robert Hunt.


_From the Illustrated London News, January 9, 1858._

It is but a few years since, when we heard with surprise, and
some incredulity, that light could be made to delineate images of
external objects upon chemically prepared tablets placed in the
camera obscura,--now photography stares us in the face at every
corner,--that which was wonderful has become familiar,--that which
was mysterious is singularly common.

In cities, we see glass houses, on at least one roof in every
street,--in villages, caravans, with Brown and Jones, photographers,
are regularly found,--on the hills we discover the tent, and in the
valleys the camera,--by the river-side there is the mysterious head
hidden in the dark curtains of a dark box,--and upon the sea-shore
the tripod-stand is securely fixed in the sands, and a biped is
evidently focusing for the next fine ocean wave,--the sketcher has
fled to his own especial solitudes, and the photographer has usurped
his place.

It has been said of the most recent photographic processes, as was
well said of the octo-syllabic verse, that it possesses "unfortunate
facilities." This is true in many respects of the positive collodion
process, by which the myriads of sad reflections on humanity are
perpetrated. Not so, however, is it with the negative process, by
which alone we can multiply the beautiful things which the solar
pencil traces with such fidelity. The labour attendant upon a
photographic tour is great, and real enthusiasm alone carries the
amateur forward. The camera obscura and the stand are a burden, and
with the tent and chemical box, they become a real load. Then there
is the uncertainty attendant upon the processes. We deal with the
nicest chemical adjustments. The balance is arranged with caution for
a certain set of conditions,--alter but one of these, and all goes
wrong. We leave home in the morning, we work in the dark all day, and
we return jaded at night, to find we have obtained--nothing.

Sensitive as the collodion process is, and charming as are the
results, when all goes on successfully, it has not hitherto been
a process which can be practised out of doors, without many
extraordinary, expensive, and troublesome appliances.

It is, therefore, with very much satisfaction that we have watched
the progress of the so-called "dry collodion processes." Nearly
all the processes that have been published,--the "gelatine,"--the
"oxymel,"--the "glycerine," and others,--have much that is excellent
in them; but it appears to us that a dry collodion process devised by
Mr. Long, of which he has recently published a description, is more
simple and effective than any other. We have seen beautiful pictures
obtained in Belgium upon plates prepared in England, and which plates
were brought to this country again before the pictures were developed.

Any man may, previously to starting on his journey, prepare, or
purchase prepared, a stock of glass plates. Armed with these and his
camera, he may proceed to

  "Where the bleak Swiss their stormy mansion tread.
  And force a churlish soil for scanty bread;"

or to that

  "------sea Cybele fresh from ocean
  Rising with her tiara of proud towers,"--

and, resting on his way, he may adjust his camera and his plate, and
in the few minutes which, under any circumstances, he would spend in
observation, he secures a picture for future study,--a photograph to
give him pleasure in the quiet of his home.

Mr. Long has published a little treatise, with which we head this
article, and by following out the simple directions which he gives,
all may succeed in obtaining the important desideratum,--a parcel
of highly sensitive plates, which can be packed in paper and stowed
away in a portmanteau, to be drawn out as occasion may require, to
be returned again to the same package (without having any of the
annoyances attendant upon a box of liquid chemicals), and a plate
which can be kept with its dormant picture quite uninjured until the
photographer, on his arrival home, at his perfect leisure, in his own
operating room, can develop the photograph which he has obtained.

Such are the facilities offered by this improvement, that we may
expect almost every traveller will avail himself of it, and thus
secure for his own portfolio, and the portfolios of his friends,
views of scenes hallowed by their historical association,--of ruins
rendered sacred from the sacred memories which still wrap them in
their shadows, as the mantling ivy clothes their crumbling walls.




                                 THE

                      =DRY COLLODION PROCESS.=


Before describing in detail the manipulations of the process
on Dry Collodion plates, it will be necessary to say a few words
on the materials and apparatus to be employed, and also to give an
account of the means of preparing the various solutions used in the
process. First,


THE COLLODION.

This being the principal material we have to use, we must exercise
great care in the selection of a sample that possesses all the
characteristics which fit it for a dry process. We must reject all
samples that possess great tenacity and contractile power: the
Collodion must not be too thick, and it must flow evenly over the
plate, and not set in ridges. The best condition for the Iodized
Collodion is that known as _powdery_, that is, being spread on the
plate and partially dry, it cannot be removed as a film, but crumbles
up on being pressed by the finger in its passage across the plate; in
fact, such a condition as would arise from using gun cotton prepared
with acids at a high temperature.

The following formula will be found to answer most admirably:

  Gun Cotton                      60 grains.
  Absolute Alcohol                 5 ounces.
  Sulphuric Æther, sp. gr. ·730   15 ounces.

The cotton is to be shaken up with the mixture of alcohol and æther,
and when dissolved, the bottle containing it must be stood aside, in
order that any undissolved particles of cotton may subside. The clear
liquid may then be decanted into a clean bottle for use.

It will be as well to test the quality of the Collodion thus prepared
before coating any number of plates with it, for, although the above
proportions are very excellent, some little latitude must be allowed
for the different degrees of solubility of the various samples of
cotton used from time to time. The film, when spread, on the glass
plate and partially dry, should not be capable of being removed in
the form of a skin, but should give before the finger and crumble up
on its being rubbed across the plate.

Should any difficulty, however, occur, it would be better to obtain
a sample of the Collodion made by an experienced hand, in order that
a fair trial may be given to the process. If the Collodion be too
contractile it will give rise to blisters in the film, and will wash
off the plate during development.

The Iodizing Solution that I have found to give the best
results in this process is made in the manner following:--

  Absolute Alcohol        8 ounces.
  Iodide of Cadmium      64 grains.
  Iodide of Ammonium     64 grains.

The iodides are to be dissolved by agitation in the alcohol, and the
resulting solution is to be carefully filtered, and preserved in a
well stoppered bottle.

The Iodized Collodion consists of--

  Iodizing Solution   2 drams }
                              } 1 ounce
  Plain Collodion     6 drams }

The Collodion should always be iodized at least twelve hours before
it is required; this interval allows any insoluble matters either
from the iodizing solution or from the Collodion itself to fall to
the bottom, and enables the operator to pour off the clear solution
into a perfectly clean bottle for use.

Next in importance to the Iodized Collodion comes


THE PRESERVATIVE SOLUTION.

Some care is required in the preparation of this solution, in order
that it may be clear and bright when finished, and not contain
particles that would be deposited in its passage over the Collodion
film when being used. The chief precaution to be observed is _not to
allow it to boil too rapidly, and not to conduct the operation over
too fierce a fire;_ attention to this will prevent many failures,
and ensure a solution in every way suited for the process.

Take one ounce of the best transparent gelatine, and throw it into
a pipkin in which has been previously placed one pint of distilled
water; set this on a slow fire, or over a lamp, until the gelatine
is completely melted; then weigh out half ounce of pure citric acid
and dissolve it in two ounces of distilled water; add this to the
solution of gelatine, stirring it during the addition with a glass
rod. The solution in the pipkin is now to be gently boiled for about
half an hour: remove it from the fire, and add sufficient distilled
water to make up the bulk of liquid to one pint. When quite cold, the
liquid in the pipkin is to be filtered through two thicknesses of
pure white blotting paper into a bottle perfectly dry and clean. We
now add to every pint of filtered preservative solution, two ounces
of alcohol of the specific gravity of ·840.

The solution thus prepared is ready for use, and should be of a pale
amber colour, without any signs of insoluble particles floating in
it; should any appear after it has been prepared for some days, a
second filtration will remove them, and render the liquid again
bright and clear.

It will be found better to prepare this solution only in the quantity
indicated above, unless the consumption be large, for, although it
will keep good for a month or more, my experience points to the fact,
that the most successful results follow the use of Preservative
Solution freshly prepared.


THE NITRATE OF SILVER BATH.

The bath for rendering the plates sensitive does not differ from that
recommended for taking negatives with wet Collodion. The formula for
its preparation may not be out of place, however, and may assist
those whose knowledge of the matter is not perfect.

  Nitrate of Silver (fused)    1¼ ounces.
  Distilled Water              1  pint.
  Iodide of Cadmium            3  grains.

Dissolve the nitrate of silver in half the water and then add the
iodide of cadmium; thoroughly agitate the mixture for five or ten
minutes, then add ½ ounce of alcohol, sp. gr. ·840, and fill up
with the remaining half of the distilled water; further agitation,
and subsequent filtration through two thicknesses of white bibulous
paper, will put us in possession of a negative bath. The nitrate of
silver being fused, and consequently, pure and neutral, and as it is
essential to obtain clean pictures that the bath should be slightly
acid in its reaction, we find it necessary to add 5 or 6 minims or
drops of pure glacial acetic acid to a bath of 20 ounces, in order
that the above condition may obtain.


THE DEVELOPING SOLUTION

Is very simple in its nature, being merely a saturated solution
of gallic acid in distilled water, to which has been added a small
proportion of alcohol of sp. gr. ·840.

The exact formula is as follows:--

  Distilled Water           1 pint.
  Alcohol sp. gr. ·840      1 ounce.
  Gallic Acid               ½ ounce.

The gallic acid will not be entirely dissolved, but that left at the
bottom of the bottle will ensure the solution being saturated; it is
better not to filter the developing solution until it is required
for use, as it is preferable to allow it to stand over an excess of
gallic acid, than for it to be withdrawn after a slight agitation
with the crystals; it is a great error to suppose that we obtain a
saturated solution of gallic acid by merely agitating the crystals
with water for a few moments.

The developing solution prepared as above directed will keep good and
in working order for some weeks, but when it becomes of a dark color,
it would be safer to reject it and prepare a fresh quantity than to
run the risk of a failure from an impure and imperfect developing
agent.


NITRATE OF SILVER SOLUTION,

For adding to the gallic acid during development, is composed of

  Fused Nitrate of Silver     30 grains.
  Distilled Water              1 ounce.


THE FIXING SOLUTION

Consists of a solution of hyposulphite of soda in water, (filtered,)
in the following proportion:--

  Hyposulphite of Soda in crystals   8 ounces.
  Rain or Filtered Water             1 pint.

The Apparatus, &c. required in the Dry Collodion process is
of the most simple kind, and consist of the following items

      Glass plates.
      Pneumatic plate holders.
      Plate holder, for cleaning the plates.
      Glass or porcelain dishes.
      Glass or gutta percha dipping bath and dipper.
      Silver hook, for lifting plates.
      Levelling stand.
      Measures, 1, 2, and 4 ounce.
      Glass funnels.
      Wash leather.
      Some clean cloths and broad camel's hair brush.
      Cotton wool.
      Bibulous paper.
  [A] The Chemicals are--
      Nitrate of silver (fused.)
      Glacial acetic acid.
      Iodized Collodion (dry.)
      Gelatine.
      Citric Acid.
      Alcohol.
      Sulphuric æther.
      Gallic acid.
      Hyposulphite of soda.
      Iodide of cadmium.
      Benzoin varnish.

[A] The dry Collodion and the various solutions, ready for use, may
be obtained of the Publishers.

In the above List we presume that the operator is in possession of a
suitable camera and lens, and the usual adjuncts of camera tripod,
&c. &c. These should all be of the best kind, otherwise it will be
impossible to obtain good results.

[Illustration]


=THE MANIPULATION.=

The process of obtaining a picture on Dry Collodion plates is in
itself a most simple and easy matter, but there are one or two
precautions that appear necessary to ensure success that cannot be
lightly neglected. In the first place, it is absolutely certain,
that if we want a clean and bright picture, we must have a plate
perfectly free from all extraneous matters, such as soap, grease,
&c. Various plans for cleaning the glass plate have been proposed,
all more or less successful, but in most of them there is one great
fault, namely, that of using a powder, as tripoli, rotten-stone,
&c. to rub off the dirt with. Now we find that in practice this
will not answer, from the almost impossibility of getting rid of
the floating particles of the powder when the plate is rendered
slightly electrical by rubbing, and as each of these particles if
it become enveloped in the Collodion film, would produce a spot on
the finished picture, we find it necessary to search in another
direction for a detergent for the glass plate to which this objection
would not apply. One soon presents itself in the form of _old waste
Collodion_--this spread on the glass plate and rubbed off again
with cotton wool, makes the best and most perfect cleanser hitherto
proposed, without any of the objections usually appended to other
materials used for the same purpose.

The next precaution necessary to be observed is, that all the
solutions should be perfectly bright and clear; they should be
absolutely free from floating particles of any kind. This is
essential, as it is impossible to obtain clean pictures without
attention to it; the floating bodies in the solution settle on the
plate, and form so many nuclei, around which, in the development of
the picture, the silver is deposited in an opaque mass, forming spots
and blemishes on the surface of the plate.

There is one precaution that cannot be dispensed with, and that
is, to be sure that the chemicals employed are of absolute purity;
without this, success is very problematical, and vexation and disgust
the sure reward of its neglect.

The process may for convenience be divided into the following
stages:--

  1.--Cleaning the plate.
  2.--Coating it with Collodion.
  3.--Rendering the plate sensitive.
  4.--Applying the Preservative solution.
  5.--Exposure in the camera.
  6.--Development of the picture.
  7.--Fixing the developed image.
  8.--Varnishing the finished negative.

CLEANING THE PLATE.

[Illustration: _Fig. 1._]

The glass plate is first to be thoroughly washed with an abundance
of water, and dried on clean cloths; it is then to be placed in the
plate holder (_Fig. 1_), and have poured over its upper side a
small quantity of old Collodion. Now take a tuft of cotton wool and
rub the Collodion all over the plate, giving the hand a circular
motion at the time: keep rubbing until the Collodion is very nearly
dry, then turn the plate in the holder and repeat the same treatment
with the opposite side; then lean the plate thus treated against a
wall, while another, or any number are put through this stage. When
a sufficient number have been so far cleaned, the plate holder is
to be carefully wiped, and the first plate--the edges of which have
also been carefully wiped with a _clean_ cloth--is to be replaced,
and treated with a smart rubbing with a wash leather, the operator
at intervals gently breathing on the plate. Both sides of the plate
being cleaned in this way, it may be removed, after again wiping the
edges carefully, to the plate box, to await the subsequent steps of
the process. Plates cleaned in this manner should look perfectly
transparent, and free from any marks of the cloth or leather, and
when breathed upon should condense the moisture of the breath in
one uniform degree over the whole surface. If patches of uneven
condensation appear, a repetition of the process must be had recourse
to.

The plate being clean, we proceed to the next step,


COATING THE PLATE.

Lay a piece of clean blotting paper on the table, larger than the
plate we are about to use; place the clean plate on this, and
then bring the pneumatic plate holder to bear on the centre of the
glass, making sure that it has laid hold firmly. We then raise the
plate with the left hand, and bring the surface upwards which was
previously on the blotting paper; it will no doubt be found that
small particles of dust have attached themselves to the plate, these
must be removed by a broad and soft camel's hair brush, kept for this
purpose only.

[Illustration: _Fig. 2._]

The Collodion is then to be poured on, as shown in the diagram (_Fig.
2_), and the superfluous quantity returned to the bottle from one of
the corners of the plate. It does not matter which of the corners is
used for this purpose, that which is most convenient to the operator
assuming the preference. If the Collodion should have a tendency to
set in ridges across the plate, a rocking motion, while the delivery
corner is in the mouth of the bottle, may be given to it, still
keeping the plate in a vertical plane. This will restore the film to
perfect evenness and freedom from irregularity of any sort. The plate
should be held in the vertical position for a few moments before
being placed on the dipper to undergo the next operation of


RENDERING THE PLATE SENSITIVE.

[Illustration: _Fig. 3._]

The plate being placed, coated side outwards, on the dipper, is to
be plunged without hesitation into the nitrate of silver bath (_Fig.
3_). This must be done without stopping, otherwise a line across the
plate will indicate, on development, the position of the plate in
the bath at the time this stoppage took place; so that if we were to
immerse the plate by a series of jerks, we should have as a result,
so many bands of unequal development in the finished picture; showing
the importance of plunging the plate into the bath without any
stoppage during its descent.

[Illustration: _Fig. 4._]

When the plate has rested for half a minute in the bath, it may be
withdrawn, and quickly re-immersed. This washing must be continued
at intervals, until the greasy appearance goes off, generally for
the space of two minutes, when the plate is to be taken out of the
bath and placed with its lower edge on a pad of blotting paper, in a
position as shown in the cut (_Fig. 4._) A fragment of blotting paper
is then to be used to absorb the moisture from the back of the plate,
and a pneumatic plate holder--which should only be used for this
purpose--is applied to it to form a support while


APPLYING THE PRESERVATIVE SOLUTION.

[Illustration: _Fig. 5._]

Taking the plate in the left hand by means of the pneumatic holder,
incline it as shown in the diagram (_Fig. 5_); then having poured
into a perfectly clean measure rather more of the preservative
solution than is necessary to cover the plate twice,[B] pour half of
it along the upper edge (A B) in such a manner, that a wave of the
solution may flow uniformly from one end of the plate to the other;
allow this to flow off into the waste pan or sink, and then bring the
plate to the horizontal position, and pour on the remainder of the
preservative solution, eight times at least, allowing it to flow
back into the measure from each corner in succession, in order that
the whole plate may be brought uniformly under its influence. The
plate is to be again placed on a piece of clean blotting paper (as
shown at _Fig. 4_), and its back once more wiped with a fragment of
blotting or papier Joseph, in order to remove any of the preservative
solution that may have run from the surface to the underside in the
previous operation. The plate thus preserved is to be reared on a
piece of blotting paper with its face against the wall until dry, and
is then to be stowed away in a plate box, perfectly light-tight to
await the

[B] A plate, 9 inches by 7, takes about 1 ounce of solution.


EXPOSURE IN THE CAMERA.

Collodion plates preserved as above directed, will keep perfectly
good and sensitive for 12 months at least; and from the appearance of
the developed image on a plate that has been kept that time, I see
at present no reason why, if preserved from the damp, they would not
keep indefinitely. In my experiments, I have never found the least
difference in sensitiveness, whether the plate be used within a few
hours of the time of its preparation, or has been kept for months;
until, however, we have had more experience in the matter, it would
be safer not to rely on plates more than 12 months old.

The time of exposure in the camera, of course varies in this process,
under the same circumstances as it does with the wet Collodion; but
I have found as a general rule, that it is better to give the plate
a full exposure than to fall into the opposite extreme: that is to
say, it is preferable to expose the plate sufficient time for the
deepest shadows to make an impression than to close the dark slide
at an earlier period, the mode of development allowing considerable
latitude in this particular. With a 3-inch single lens, 16-inch
focus, with a ½-inch stop, the usual time for a bright landscape
will be about 5 minutes; this of course is merely an approximation
to the time of exposure, the exact time can only be arrived at by
experience. I do not think I can do better than follow the plan
adopted in my "Practical Photography," of giving instances of
under and over exposure, as a means of educating the tyro in the
appearances that result from these conditions of the plate.

If the exposure has been of too short duration, the image will come
out under the developing solution with difficulty; and after a
continued immersion in it will only present the high lights, the deep
shadows not being represented, or, if so, in so faint a manner as to
be useless in the picture.

An over exposed plate, when treated with the developing solution,
will almost immediately give indications of the picture; and in a
few minutes, the whole of the picture, _deep shadows and all_, will
come put in unnatural force; on looking through the picture thus
produced, we shall observe a great flatness in it, there is a want
of contrast between the various parts, and although by continuing
the development we might obtain a tolerably intense negative, the
resulting picture would be flat, meagre, and unsatisfactory: on the
contrary, a plate that has been exposed for the correct time, will
comport itself very differently under development from the foregoing.

The sky and high lights will first appear, then the half tones, and
lastly, the parts of the picture that were in deep shadow will show
themselves; this effect should take place in about five minutes from
the time of immersion in the developing bath: a picture that comes
out sooner than this, is, as a general rule, over exposed; and one
that is much after the five minutes before it makes its appearance,
may be considered as under exposed.

We trust that the above instances may be of service in indicating the
average time required for an exposure of the plate, but we must ask
the reader not to take the figures given as actual values, but merely
as very close approximations to the truth. We will imagine the plate
to have been properly exposed, and proceed to


THE DEVELOPMENT OF THE PICTURE.

It is not necessary that the picture should be developed immediately
after exposure in the camera; any time that is convenient to the
operator may intervene between the processes, provided the aggregate
time before and after exposure does not exceed the limits of keeping
power of the plate.

The development of the picture may be conducted in two ways, either
by immersing the plate in baths or dishes, or by placing it on the
levelling stand and treating it with the solutions, in their proper
order, as detailed below. Each plan possesses certain advantages, but
it is of little consequence which one is followed. Perhaps there is
less danger of the film washing off if the plate be treated on the
levelling stand, and on the other side with large plates it is more
difficult to cover them evenly with the developing solution than it
is simply to immerse them in a pan of solution. We say to the reader,
try both ways, and make your own selection.

The plate upon being removed from the camera is placed face upwards
in a porcelain or glass dish of a convenient size (not too large),
and sufficient distilled water is to be poured over it to cover
the surface thoroughly--this is for the purpose of softening the
preservative solution, and must be allowed to remain on the plate
for five minutes; the plate is then to be lifted in and out of the
water by means of the silver hook. This done, remove the plate to
a perfectly clean dish, and pour carefully over it the developing
solution, composed of

  Saturated Solution of Gallic Acid (p. 10)   8 ounces.
  Solution of Nitrate of Silver (p. 10)       2 drams.
           THOROUGHLY MIXED.

In a few minutes the picture will begin to make its appearance,
and will gradually unfold its details under the influence of the
developer, until the whole of them are apparent; on raising the
plate, however, when this stage of development is reached, and
viewing it by transmitted light, the picture will appear weak
and poor; we must now remove the plate from the bath, and add 2
drams more of the nitrate silver solution, and having thoroughly
mixed it with the gallic acid already in the dish, we return the
partially developed plate, which in the course of a few minutes
will have acquired a great amount of intensity,--the exact degree
can be regulated by the time of immersion: when the picture appears
sufficiently intense, it is to be removed from the developing dish,
and a gentle stream of water is poured over it, in order to remove
any adhering developing solution, and stop all further reducing
action on it.

During the whole time of the development, the gallic acid should
remain quite clear; it will become slightly discoloured before the
end of the development, but it ought not at any time to become muddy,
or it will deposit a sort of sandy sediment on the surface of the
plate, which cannot be removed by subsequent washing.

The usual time occupied in the development of a successful picture
is from 20 to 30 minutes, it might be developed much quicker by
using pyrogallic acid, but at present I give the preference to the
developer I have described, as I believe it to be more certain, and
more under the control of the operator than the pyrogallic acid; and
further, as it is not necessary to watch the development all the time
it is going on, there can be very little saving of time in the more
rapid method of bringing out the latent picture.

The picture being washed free from the adhering developing solution,
is to be placed on the levelling stand, and subjected to the seventh
part of the process--


FIXING THE DEVELOPED IMAGE.

This is accomplished by pouring over the surface of the plate
sufficient solution of hyposulphite of soda (p. 15) to thoroughly
cover it, this will dissolve out the unaltered iodide of silver, and
give us a clear and bright picture, in which the deep shadows should
be as transparent as the glass itself, and the high lights as dense
as a piece of metal, the intermediate tones assuming their proper
positions according to the intensity of the light that was concerned
in their formation.

When the whole of the yellow iodide of silver is removed, the fixing
solution may be thrown off, and the plate must be treated with an
abundance of water; too much cannot well be given at this stage, as
the hyposulphite adheres with great tenacity to the plate, even
after a good washing. The back of the plate must be washed as well
as the front, for I have found that a neglect of this precaution has
ruined many a fine negative; the hyposulphite remaining at the back
finding its way by capillary attraction to the surface, and once
there, its destructive qualities are sure, sooner or later, to render
themselves evident.

The picture being thoroughly washed, and either dried spontaneously
or by the fire, has only to be covered with a film of varnish. And
now comes the last operation, of


VARNISHING THE FINISHED NEGATIVE.

Benzoin varnish is the best coating that can be given to a Collodion
negative. It resists the action of pieces of grit; it does not crack;
and, above all, it does not, like amber varnish, split off the
picture on the slightest friction.

The application of this varnish is a very simple matter. The negative
is to be again placed on a pneumatic plate holder, and the varnish is
to be poured on to the surface in precisely the same manner as the
Collodion was at the commencement of the process, the superfluous
quantity being returned to the bottle: in a few moments the varnish
will be quite dry and hard, and the plate may be handled with perfect
safety.

I may mention, as a precaution, in varnishing the plate, that it
is better to perform that operation in a still atmosphere; as the
solvent of the gum being chloroform and very volatile, if it were
conducted in a current of air, there might be some difficulty in
obtaining an even coating to the picture.

In concluding this description of a process, which is at once simple
and certain, I would ask the patient attention of those who may do me
the honor of repeating my experiments. I have endeavoured to render
the details of the process as intelligible as possible, and if I have
succeeded in advancing the art of Photography only one step by so
doing, I consider that it is an ample return for hours and days spent
in anxious thought and laborious experiment.


                               FINIS.


                     SPECIAL LIST OF REQUISITES

                               FOR THE

                      =DRY COLLODION PROCESS,=

                             SUPPLIED BY

                        Messrs, BLAND & LONG,

             Opticians, & Photographic Instrument Makers

                            TO THE QUEEN,

                    =153, FLEET STREET, LONDON.=

       *       *       *       *       *

                           BLAND & LONG'S

                      =IODIZED DRY COLLODION.=

This preparation will keep for an indefinite period, and can be
exported to any climate, without risk of deterioration.

_Half-pints, 10s.; Pints, 18s._

       *       *       *       *       *

                           BLAND & LONG'S

                      =PRESERVATIVE SOLUTION,=

                   READY FOR USE.--_1s. per pint._


                           BLAND & LONG'S

                         =BENZOIN VARNISH,=

                FOR PROTECTING THE FINISHED NEGATIVE.

                            _1s. per oz._

This varnish does not require the plate to be warmed; but dries
instantly, leaving a perfectly hard transparent coating on the
picture.

       *       *       *       *       *

                      =NITRATE OF SILVER BATH,=

                  FOR BLAND & LONG'S DRY COLLODION,

            Ready for immediate use.--_7s. 6d. per pint._

                  *       *       *       *       *

                          =PURE CHEMICALS.=

                                          _s._  _d._

  Fused Nitrate of Silver, absolutely pure   4    6  per oz.
  Glacial Acetic Acid                        1    0    "
  Pure Gelatine                              0    6    "
  Pure Citric Acid                           0    6    "
  Gallic Acid, pure                          1    6    "
  Iodide of Cadmium                          3    0    "
  Hyposulphite of Soda                       1    0  per lb.
  Pure Sulphuric Æther                       0    6  per oz.
  Absolute Alcohol                           0    6    "

       *       *       *       *       *

                     FOR THE PRICES OF APPARATUS

                                 SEE

                          =BLAND & LONG'S=

           Illustrated Catalogue of Photographic Apparatus

                _Sent free by post, on application._


                              SENSITIVE

                       =DRY COLLODION PLATES,=

                  READY FOR EXPOSURE IN THE CAMERA.

                         (=LONG'S PROCESS.=)

                  *       *       *       *       *

Messrs. Bland & Long are now prepared to supply these
plates, carefully secured in sealed cases, with full directions for
exposure and development, of all sizes and in any quantity, at the
following prices:--

              Per Doz. |                Per Doz.
                 s. d. |                £.  s. d.
  4¼ × 3¼        5  0  |  7  ×  6       0  14  0
  5  × 4         6  6  |  8½ ×  6½      0  18  0
  5½ × 3⅜        6  0  |  9  ×  7       1   1  0
  6¼ × 3⅜        8  6  | 10  ×  8       1   6  0
  6½ × 4¾        8  6  | 11  ×  9       1  13  6
  6¾ × 3¼        8  9  | 12  × 10       2   0  0
  6  × 5         8  6  | 15  × 12       4   0  0

LARGER OR OTHER SIZES TO ORDER.

The advantages of a certain and simple Dry Collodion Process are so
obvious to those who have practised Photography in the open air, that
we feel it is merely necessary to introduce the above list to their
notice with as few remarks as possible.

We would, however, mention a few particulars connected with the
process for the information of those who have not hitherto practised
the Dry Collodion process, as detailed by Mr. Long.

The plates as prepared for sale, are hermetically sealed in an
envelope perfectly impervious to air and moisture, they can therefore
be exported to any climate without risk of deterioration.

Plates prepared by Mr. Long's process will keep sensitive for almost
an indefinite period, and can be developed at any time without
regard to the date of exposure; this, it will be seen, is of immense
advantage to the tourist, as he can delay the development of the
whole of his plates until his return.

To those Photographers whose inclinations or want of leisure will not
admit of their carrying through the first preparation of the plate,
these Dry Sensitive Plates will be found invaluable, enabling their
whole energy to be directed to the more careful selection of subject.

The plates being dry, there is no danger of dust settling on their
surfaces; this point will be appreciated by every Photographer.

The development of the pictures can be conducted in any room whence
the light can be excluded--as the process is simple and clean--three
dishes being the only requisites in point of apparatus.

To Officers, Engineers, and Architects, these Dry Plates offer
a desideratum of no small value, as they are _always ready for
use_, occupy very little room in travelling, and can be used under
circumstances which would preclude the adoption of any process that
had to be carried out on the spot.

       *       *       *       *       *


                            BLAND & LONG,

            Photographic Instrument Makers to the Queen

                     153, FLEET STREET, LONDON.


                                 THE

                     =DRY COLLODION PROCESSES.=

                  *       *       *       *       *

          Messrs. BLAND & LONG have invented the following
                           simple means of

                 =CHANGING THE DRY COLLODION PLATES=

        while working in the fields. The plan has been in use
                for some time, and answers perfectly.

                  *       *       *       *       *

                     _Price according to size._

               _Adapted to Stereoscopic Camera, 15s._

                  *       *       *       *       *

[Illustration]


DESCRIPTION AND DIRECTIONS FOR USE.

No matter what process we employ to retain the sensitiveness of our
plates, it is most objectionable that the glasses should be made to
slide by their gravity from the plate-box to the slide; for if we
employ either honey, glycerine, or oxymel as preservative agents, the
chances are considerably in favor of an amount of dust settling on
the surface, the dust being in a great part formed by the attrition
of the roughened edges of the plate against the plate-box. Another
inconvenience attending the use of a box when the plate has to slide,
is the danger that exists under that arrangement of ripping the film
from the edges of the plate by the friction against the groove in the
box which holds it. These may appear very trivial matters, but they
are nevertheless great drawbacks to successful operations.

We may mention that the plan we are about to describe is equally
applicable to all Cameras of moderate size. We will, however, take
our description from the form of apparatus adapted to a double lens
Stereoscopic Camera.

The Camera (A) is furnished at its back with two wires (B). On these
wires slides the plate-box (C), which has previously been fitted at
its sides with two sockets (D). Just inside the back of the Camera
box is a spring (E), and on the top of the Camera is a button (F),
which secures the dark slide in its place.

We now slide the box of prepared plates (C) on to the wires (B), the
lid of the box opening from the Camera; we then stretch over the
whole affair, the black light proof covering (G); this completes the
arrangement, and now for the mode of operating.

The opaque covering is furnished at its side with two elastic rings.
Into these thrust the hands, so that the rings may firmly encompass
the wrist. Then open the plate-box, and throw the lid quite back.
Next unbutton the door of the dark slide, and raise it until the
spring (E) flies underneath it, and retains it in a horizontal
position. This we will presume to be done with the right hand; the
left hand being engaged as soon as the door is opened, in holding
the plate that is already in the back in its place. The right hand
being now at liberty, comes to the assistance of the left, and the
plate that has undergone exposure is safely transferred to the vacant
groove in the plate-box. This accomplished, the next plate is to
be placed in the back, and the same operations gone through in the
inverse order, the left holding the plate in its place, while the
right releases the door from the influence of the spring (E), and
re-buttons it, leaving the plate quite safe in the dark slide.

When we require to focus for a fresh picture, it is only necessary
to remove the dark covering from that part of the Camera where the
ground glass is placed. The picture can be seen without removing the
plate-box or the whole of the covering.

It is obvious that there is no limit to the number of glasses that
can be taken to the field of operations. In this way, several boxes
holding a dozen each, can be strapped together and placed on the
Camera, one by one, as occasion or opportunity may direct.

                  *       *       *       *       *

              H. Silverlock, Printer, Doctors' Commons.


                      =PRACTICAL PHOTOGRAPHY,=

                         ON GLASS AND PAPER,

                             A Manual,

         CONTAINING SIMPLE DIRECTIONS FOR THE PRODUCTION OF

           =PORTRAITS, VIEWS, &c. BY THE AGENCY OF LIGHT,=

                            INCLUDING THE

   =Collodion, Albumen, Calotype, Waxed Paper, and Positive Paper
                             Processes.=

                         By CHARLES A LONG.

           _Fourth Edition, price 1s.; per Post, 1s. 2d._

                  *       *       *       *       *

                =ILLUSTRATED PHOTOGRAPHIC CATALOGUE,=

                            FREE BY POST.

                  *       *       *       *       *

                            =SPECTACLES:=

                  WHEN TO WEAR AND HOW TO USE THEM.

                            ADDRESSED TO

                   =THOSE WHO VALUE THEIR SIGHT.=

                         By CHARLES A. LONG,

                 THIRD EDITION. POST FREE, SIXPENCE.

                  *       *       *       *       *

                                ALSO,

                 A DESCRIPTIVE AND GENERAL CATALOGUE

                                 OF

               =SCIENTIFIC & EDUCATIONAL INSTRUMENTS=

                                 AND

                       CHEMICAL PREPARATIONS,

               Manufactured and Sold by BLAND & LONG,

 =OPTICIANS, PHILOSOPHICAL, PHOTOGRAPHICAL, AND CHEMICAL INSTRUMENT
                              MAKERS,=

                       AND OPERATIVE CHEMISTS.

                           _Free by Post._

                PUBLISHED BY BLAND & LONG, Opticians,

          Philosophical and Photographical Instrument Makers
                             to the Queen,

                         163, FLEET STREET.


       *       *       *       *       *


Transcriber Note

Minor typos corrected. Images moved to prevent splitting paragraphs.







End of Project Gutenberg's The Dry Collodion Process, by Charles Long