Improvements in the Production of Collodion Photographic Films or Surfaces of Exalted Sensitiveness.
Year: 1888

page_text: Date of Application, 11th May, 1888
Complete Specification Left, 2nd Feb., 1889
Complete Specification Accepted, 2nd Mar., 1889
TRUVIDIONALE IUATION.
Improvements in the Production of Collodion Photographic Films
or Surfaces of Exalted Sensitiveness.
I RICHARD NORRIS, of No. 3 Birchfield Road Aston near Birmingham in the County
of Warwick Doctor of Medicine do hereby declare the nature of this Iuvention to be
as follows:-
The photographic process commonly called the collodion process has of late fallen
largely into disuse in consequence of the higher degree of sensitiveness possessed
by the dry gelatine plates or films now commonly used in the practice of photography.
Collodion possesses some advantages over gelatine as a photographic vehicle which
advantages have hitherto been more than counterbalanced by the inferior sensitiveness
of collodion.
The object of my invention is to increase the sensitiveness of collodion photographic
films or surfaces and consists of the methods herein after described of preparing the
said films or surfaces whereby they are made equal or superior to dry gelatine films
in their sensitiveness to light.
According to one of my improvements I add the silver salt to the collodion instead
of impregnating the collodion with a soluble iodide or bromide or other haloid salt or
salts and I immerse or float the plate or paper coated with the said collodion in or
on a bath containing an aqueous solution of the iodide or bromide or other haloid salt
or salts or mixtures of the same. By this method of procedure a greater range in the
selection of the haloid salt or salts is secured as many of these salts are insoluble in a
mixture of alcohol and ether which is the menstruum in which gun cotton is dissolved
to make collodion.
I will describe my invention in connection with a photographic film on a glass
plate.
Having coated the plate with collodion charged with a salt of silver (nitrate of silver
for example) I immerse it in a bath of iodide bromide or other haloid salt of potassium
sodium or ammonium or the like. After treatment in this bath the plate is washed
in water and afterwards submitted to the action of dilute solutions of soluble iodides

page_text: and of alkalies such as potash or ammonia or the alkaline salts of such and allied
bases. The object of this last described treatment is to convert the silver bromide or
chloride into a compound salt of iodo-bromide or iodo-chloride of silver or iodo-bromo-
chloride of silver.
The plate is next treated with a weak solution of gelatine either with or without.
washing. It may in this state be used as a wet plate or the plate after washing may
be saturated with any of the ordinary preservatives such as a solution of gum starch
dextrine gelatine sugar or analogous substance. It is then dried either spontaneously
or by the application of heat.
According to another of my improvements I add solutions of iodides bromides or
chlorides or mixtures of these in a mixture of ether and alcohol to the collodion as
usual and immerse the plate after its collodion film has set in a bath of nitrate of
silver saturated with iodo-nitrate of silver. This bath also requires the addition of
from forty to one hundred minims of nitric acid to cach ounce of bath. The plate
on removal from the bath is washed with water and submitted for a time to the action
of a weak solution of gelatine and afterwards to the action of a dilute solution of
iodide of potassium or ammonium or the like.
The plate may now be used as a wet plate or washed and preserved in the way
hereinbefore described and dried and used as à dry plate.
My improvements are applicable to the preparation of photographic plates or films
by means of collodion emulsion. In carrying this modification of my invention into
effect I prepare collodion emulsion with excess either of soluble haloid salts or of silver
salts. If the first method be employed I treat the emulsion or film with gelatine
alkali and iodide. If the second method be employed I treat the emulsion or film
with gelatine or iodide only.
Plates prepared by the processes described are equal or superior to gelatine plates
in their sensitiveness to light. They may be readily developed either by ferrous
oxalate or alkaline pyrogallic acid and fixed either with solution of hyposulphite of
soda or cyanide of potassium. These plates develop rapidly. They are not liable to
fogging or blistering. They require but little washing after fixing and may be dried
spontaneously or by the application of heat. The exposing of such plates in the
camera obscura their development fixing and drying and complete preparation for
printing from may be effected with a quarter of an hour.
When a paper or flexible support for the photographic film is used in place of a
glass plate the coated support may be floated on the solutions instead of being
immersed in them.
The strengths of the various solutions I employ and the temperatures to be observed
at the several stages of the processes I do not consider it necessary here to describe
as I reserve these and other details for my complete specification.

page_text: or Surfaces of Exalted Sensitiveness.
I RICHARD NORRIS of No. 3 Birchfield Road, Aston, near Birmingham, in the County
of Warwick, Doctor, of Medicine, do hereby declare the nature of my Invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
The photographic process commonly called the collodion process has of late fallen
largely into disuse in consequence of the higher degree of sensitiveness possessed by
the dry gelatine plates or films now commonly used in the practice of photography.
Collodion possesses some advantages over gelatine as a photographic vehicle
which advantages have hitherto been more than counterbalanced by its inferior
sensitiveness.
The object of my invention is to increase the sensitiveness of collodion photographic
films or surfaces and consists in the methods hereinafter described of preparing the
said films or surfaces, whereby they are made equal or superior to dry gelatine plates
in their sensitiveness to light. These methods may be designated the alkaline and acid
bath and emulsion processes.
I will describe first the alkaline bath process. In this process I add the silver salt
to the collodion instead of impregnating the collodion as is usual with a soluble iodide
or bromide or other haloid salt or salts because by this method of procedure a greater
range in the selection of the haloid salt or salts to be used as a bath is secured, for
many of these salts are insoluble in a mixture of ether and alcohol which is the
menstruum in which gun cotton (pyroxyline) is dissolved to make collodion. To make
one ounce of such a collodion I dissolve seven grains of pyroxyline made at a tem-
perature of about 200 degrees Fahrenheit in a mixture of two drachms of ether and
one, drachm of alcohol. I then take twenty six grains of very finely powdered silver
nitrate and mix it in a test tube of suitable capacity with eighty drops of glycerine
and stir it continuously with a glass rod till most or all of the silver nitrate is dissolved.
I then add gradually to this solution five drachms of absolute alcohol and finally add
by degrees the whole of this to the solution of pyroxyline. By the use of glycerine
instead of alcohol for dissolving the silver salt the said salt is most conveniently
introduced into the collodion. Alcohol may however be used for that purpose.
Glass plates, paper or other surfaces may be coated with the prepared collodion
described and then submerged in or floated upon a solution of the soluble baloid salt
or salts to form a film containing iodide, bromide or chloride of silver or mixtures of
these.
I will describe my process in connection with a photographic film on a glass plate.
Having coated the plate with collodion charged with a salt of silver, nitrate of
silver for example (which collodion may be called "argentised collodion") I submerge
the coated plate in a bath of iodide, bromide, chloride or other compound haloid salt
of potassium, sodium, animonium or the like for a period varying from five to forty

page_text: five minutes. Films produced in such baths are much more sensitive after the bat
has become charged with ether and alcohol, hence in preparing the said films I ad
ether and alcohol to the bath of haloid salts.
A bath of the following composition answers well in practice.
Potassium bromide froin 35 to 70 grains; distilled water half an ounce; methylate
alcohol of specific gravity 830 half an ounce; methylated ether of specific gravity 711
thirty six minims. The longer the plate or film remains in such a bath (within the
limits I have given namely from five to forty five minutes) the more transparent and
sensitive it will become. It will also undergo those well known molecular changes
which modify the tint of the silver haloid salt to transmitted light from ruby to blue
and green. The temperature of the bath should be about 76 degrees Fahrenheit.
The plate having remained a suitable time in the bath (according to the sensitiveness
desired).it is withdrawn and washed with water and submitted to the action of a dilute
alkaline solution, such, as a solution of potash soda ammonia or the alkaline salts of
these and allied bases. The method I usually adopt is to dissolve 240 grains of caustic
potash (hydrate) in-8 ounces of distilled water as a stock solution; of this I take 40
minims and add it to 8 ounces of water to make the alkaline bath. The plate is
allowed to remain in this bath from 10 to 15 minutes and is then transferred to a
solution of gelatine containing preferably forty grains of dry gelatine to a pint of water in
which it may remain from 15 to 45 minutes. It is next passed into a dilute solution of a
soluble iodide or bromide such as iodide or bromide of potassium, aminoniuni sodium
or the like in which it may remain from 10 to 15 minutes. The iodide bath which is
preferable may be thus prepared iodide of potassium 8 grains; water S ounces;
half a drachm of this solution is added to S ounces of water to make the bath.
The object of this last described treatment is to convert the silver bromide, chloride
or chloro-bromide into corresponding compounds of iodo-bromide, iodo-chloride and
iodo-bromo-chloride of silver. These iodine compounds can only be successfully pro-
duced by this method of displacement for if a soluble iodide is added to the bath
resensitising with silver nitrate becomes necessary. The employment of the iodide on
the other hand confers great advantages both as to sensitiveness, freedom from fog and
susceptibility of development. The plate after the treatment described may be washed
in water. Having at this stage acquired its full sensitiveness it may either be used at
once as a wet plate or be saturated with any of the well-known preservatives such as
gum, gelatine, dextrine sugar or analogous substances and either be dried spontaneously
or by the suitable application of beat. The preservation does not either exalt or
diminish the sensitiveness.
It is scarcely necessary to remark that all the processes described as well as those
hereinafter described excepting the, preparation of the collodion and solutions must e
conducted in a low non-actinic light.
"
In another of my improvements which I have referred to as the acid bath process I
make collodion after the customary method, that is, I charge it with iodides, bromides
or chlorides or mixtures of these salts soluble in alcohol and ether. I submerge the
plate or surface coated with such prepared collodion for periods varying from five
to forty five minutes in a nitrate of silver bath charged with salts which are com-
pounds of haloid silver salts with silver nitrate; that is, iodo-nitrate of silver, bromo-
nitrate of silver, chloro-nitrate of silver or compounds of these such as iodo-bromo-nitrate
of silver iodo-chloro-nitrate of silver and iodo-bromo-chloro-nitrate of silver. 1 form
these salts in their crystalline state and add them in quantities sufficient to saturate the
silver solution used as a bath. The full sensitiveness conferred by baths. of the kind
last described is only obtained by the use of unusual proportions of nitric acid. From
40 to 100 minims of dilute nitric acid of specific gravity 1.101 to each ounce of bath
solution. A larger proportion confers higher sensitiveness but it produces rottenness of
the film. A bath of the kind referred to may have the composition and may be prepared
as follows. Silver nitrate 560 grains; dilute nitric acid 640 minims; distilled water
8 ounces. Add the acid to the water and dissolve in it the silver nitrate; lastly add
iodo-bromo-silver-nitrate or allied compound silver salts to saturation.
These compound salts of silver haloid and silver nitrate are prepared by adding silver

page_text: iodide, bromide or chloride or silver iodo-bromide or silver iodo-bromo-chloride to
concentrated hot solutions of silver nitrate to saturation. When the solutions become
quite cold'the compound salts will be deposited and may be collected and transferred
to the silver solution prepared for the bath. This solution should then be kept in a
warm place for several days and shaken or stirred. at intervals to insure saturation..
The film or plate on removal from the bath is washed with distilled water and. as in the
former process passed through the gelatine and iodide baths after which it may b
_be.
washed in water and used as a wet plate or preserved as in the manner hereinbefore
described, dried and 'used as a dry plate. In this process the alkaline bath is
'oniitted.
The ultimate sensitiveness of the photographic surface obtained will be related both:
to the length of time the film is in the bath and to the temperature of the latter which
may be used from 84 to 150 degrees Fahrenheit. These films progressively undergo
the well known molecular changes from ruby to blue by transmitted light while in the
silver bath.
My invention further consists in the preparation of photographic plates or films by
means of collodion emulsion inasmuch as these emulsions whether prepared with the
soluble.bromide or the silver nitrate in excess may have exalted sensitiveness conferred
upon them by the methods described in the foregoing bath processes. In an emulsion.
with soluble bromide in excess the emulsion or film is treated after washing with the
alkaline bath or wash and subsequently with the solutions of gelatine and alkaline
iodide and finally preserved and dried as in the previously described processes.
In the case of an emulsion in which the silver nitrate is to remain in excess.
the emulsion must be prepared in the first instance with a solution of silver nitrate
saturated as in the acid bath process with iodo-nitrate of silver; iodo-bromide or
chloride of silver or mixtures or compounds of these salts.
After washing the emulsion the film must be treated with solutions of gelatine and
iodide and washed dried and preserved as in the preceding cases.
In the preparation of an alkaline emulsion that is one with the soluble bromide in.
excess the greatest sensitiveness is obtained by the use of the bromides of the alkalies
rather than those of the earths and heavy metals.
Plates or films prepared by any of the processes hereinbefore described are equal if
not superior to gelatine plates in their sensitiveness to light. They may be readily
developed with the ordinary chemical developers such as ferrous oxalate of potash or
alkaline pyrogallic acid or hydroquinone and fixed either with solutions of hyposulphite
of soda or cyanide of potassium.
The exposing of plates treated according to my invention in the camera obscura,
their development, fixing and drying and complete preparation for printing from may
be effected in about a quarter of an hour.
In the description of my invention hereinbefore given I have indicated the particular
materials which I prefer to employ and the proportions which I have found to answer
well in practice. I have also described the best methods with which I am acquainted
of conducting the processes involved in the practice of my invention. But I wish it
to be understood that I do not limit myself to the use of any particular materials as
materials chemically analogous to those I have described may be employed neither do
I limit myself to the strengths indicated of the solutions employed nor to the precise
order of their application nor to the temperatures at which the processes are conducted.
Having now particularly described and ascertained the nature of my invention and
the manner in which the same is to be performed I declare that I claim as my invention
of "Improvements in the production of collodion photographic films or surfaces of
exalted sensitiveness" :-
First The method herein described of producing a silvered or argentised collodion
containing such an amount of silver nitrate as will form when treated with an aqueous
solution of iodide bromide or other analogous salts of potassium, sodium or ammonium
or other base, a film or surface of sufficient thickness and density to give intense images
and insure freedom from halation substantially as described.

page_text: Secondly The improvement of the sensitiveness of such films or surfaces by..the
addition of alcohol and ether to the before, mentioned aqueous, solutions.. of iodide,
bromide or other analogous salts of potassium, sodium or ammonium or other base
substantially as described.
Thirdly The use of alkalies, alkaline carbonates, or allied salts as sensitisers of
films or surfaces or emulsions which have been produced in an excess of soluble haloids
substantially as described.
Fourthly The use of a weak solution of gelatine not as a vehicle or preservative
but as a direct sensitiser of the haloid silver salts substantially as described.
Fifthly—Treating the film or surface with very dilute solutions of iodides and
bromides to convert the bromides or chlorides of silver in the film or surface or
in the emulsion into compound salts of iodo-bromide or iodo-chloride or iodo-
bromo-chloride of silver possessing more exalted sensitiveness and finishing the film or
surface substantially as described.
Sixthly The employment of collodion charged in the usual way with haloid salts of
potassium, sodium, ammonium and the like and treating the film or surface obtained
by the use of the said collodion with a solution of silver nitrate charged preferably to
saturation with iodo- or bromo-nitrate of silver or compounds of these and other
analogous salts or salts of silver and containing free nitric acid substantially as
described.
Seventhly The employment of the materials and processes referred to in the pre-
ceding claims to the production of emulsions for the formation of photographic films
or surfaces substantially as described.