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Dr Tl Phipson's Process 1861

Take a solution of perchloride of iron and, having precipitated the
peroxide with ammonia, collect the precipitate on a filter and wash it
with boiling water. Add the precipitate in excess to a warm solution of
oxalic acid. A beautiful emerald green solution is obtained, which must
be a little concentrated by evaporation and then set aside in a dark room
for use. The paper is floated for ten (?) minutes upon the green solution
of ferric oxalate, to which has been added a little oxalate of ammonia and
hung up to dry in the dark.

Expose under a negative for from ten to twenty minutes, according to the
weather, and wash well the paper with rain water. Spring water will not
do on account of the lime it may contain, which will form oxalate of lime
in the paper (insoluble). When all the non-decomposed oxalate is washed
from the proof, a feeble image of oxalate of protoxide of iron, scarcely
visible, is left on the paper. To develop it and to obtain the vigor, the
tone and color of silver prints proceed as follows:

Plunge the proof for a little while in a (weak) solution of permanganate
of potassium to which a few drops of ammonia have been added; in the bath
the image becomes brown and distinctly visible. It is then withdrawn and
immersed in a solution of pyrogallic acid for half an hour, after which it
is washed and dried.

The image thus obtained can hardly be distinguished from silver prints;
the tone is soft, brilliant and permanent.

This process is quite original and interesting. The theory is as follows:
Under the action of light the ferric oxalate is reduced in the ferrous
salt, insoluble, which, after the print has been cleared from the ferric
oxalate, is oxidized and reduced into ferric oxide by the alkalized
permanganate, the latter then forming colored compounds with reagents.

It has been lately published in England under the name of "kallitype," a
new process--or old, ad libitum--which consists in developing the image in
ferrous oxalate by a peculiar silver compound whose formula is given
below. The paper is prepared by brushing with a strong solution of
neutral ferric oxalate dried rapidly--which is a sine qua non when using
deliquescent salts; and after exposure the image is developed, etc.

Silver nitrate 50 grains
Sodium citrate 800 grains
Potassium bichromate 1 to 2 grains
Water 10 ounces

"Dissolve the silver nitrate in 1 ounce of water, the citrate and
bichromate in the remainder and mix. The precipitate--silver citrate and
chromate--is then dissolved by adding 1 dram of ammonia .880, and after 35
drops of strong nitric acid has been added the solution is ready for use."

This process reminds us that of Robert Hunt (1842), and that of more
recent date (1863), of Borlinetto, who developed the image in black with a
silver nitrate alcoholic solution, 1:500, and after washing the picture in
a solution of citric acid, 1:10, fixed it by aqueous ammonia. But,
although that is not absolutely necessary, we would advise one working
this, or similar processes in which a silver salt is employed for
developing, to fix the image, after treatment with citric acid to clear
the proofs from iron salts, in a solution of ammonium sulphocyanate--which
has not the injurious effect of sodium thiosulphate (hyposulphite)--in
order to prevent the paper to be tinged by the reduction of the silver
nitrate which is mechanically retained in its fiber.

The solution of ammonium sulphocyanate should be compounded with auric
chloride to tone the picture at the same time it is fixed; thus:

Ammonium sulphocyanate 35 parts
Gold terchloride 0.15 part
Water 350 parts

The solution can be used over again.

In the processes devised by Dr. Phipson, Monckhoven and other authorities,
the double ammonio-ferric oxalate is rightly recommended instead of the
simple oxalate. Not only is the preparation more sensitive to the
luminous action, but better half tones are obtained. As usual, it is
advantageous to size the paper with starch.

The ammonio-ferric oxalate is prepared by precipitating ferric chloride or
sulphate by aqueous ammonia, then washing the precipitate collected on a
filter until the washing water be neutral or does not evolve the smell of
ammonia. The precipitate is then placed in an evaporating dish, and by
small quantity is added a hot solution of ammonium oxalate until it is
nearly (not entirely) dissolved, when the solution is set aside for a few
hours, then filtered and evaporated to crystallization. For use, the
crystals of ammonio-ferric oxalate are dissolved in the proportion of 1
for 5 of distilled water. The solution as well as the crystals should be
kept in the dark.

If one object to the trouble of crystallizing, the solution can be
prepared by dissolving the ferric oxide in a hot solution of 30 parts of
ammonium oxalate and 25 parts of oxalic acid in 180 parts of water
observing that the oxide must be in excess.(42)

The following sensitizing solution gives also excellent results:

Ammonio-ferric oxalate 10 parts
Ammonio-ferric lactate 4 parts
Water 100 parts

After exposure, which varies from five to ten minutes, according to the
intensity of the light and the printing quality of the negatives, the
picture appears negative from formation of ferrous oxalate. It may be
developed in a great many ways: by a solution of silver nitrate at 2 or 3
per cent. of water acidified slightly by an organic acid--citric acid, for
example--or a diluted solution of ammonio-nitrate of silver, which most
likely constitutes the best developer; the image is black and consists of
metallic silver and ferric oxide, with formation of silver oxalate, which
dissolve in the ammonia. If the print be treated by a weak solution of
aqueous ammonia, the image turns green, then brown, and if, before the
latter coloration is obtained, gallic acid or pyrogallol be added, the
image becomes bluish-black or brown-black. In the same circumstances
tannin (gallo-tannin) produces a blue-black image; catechu-tannin(43) and
quino-tannin give green, etc. Employed as a developer, potassium
ferricyanate develops an image in prussian blue, and auric chloride one in
the characteristic violet metallic gold. To fix the images obtained by
the latter reactions, it suffices to wash them in a few changes of water,
and, if developed with silver, they can be toned by any of the alkaline
solutions of auric chloride used in the printing out silver process, etc.

The photographs obtained by all these processes are permanent.





Next: Dr Jb Obernetter's Process 1863
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