IMPROVE- MENTS IN THE APPLICATION OF EOSINE IN PHOTOGRAPHIC PROCESSES
Year: 1883

page_text: LETTERS PATENT to Charles Denton Abel of No 28 Southampton Buildings
""
Chancery Lane in the County of Middlesex for an Invention of "IMPROVE-
MENTS IN THE APPLICATION OF EOSINE IN PHOTOGRAPHIC PROCESSES
Communicated to him from abroad by Pierre Alphonse Attout, called Tailfer,
and John Clayton, both of Paris, France.
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel at the
Office of the Commissioners of Patents on the 8th January 1883.
CHARLES DENTON ABEL of N° 28 Southampton Buildings, Chancery Lane in
the County of Middlesex "IMPROVEMENTS IN THE APPLICATION OF EOSINE IN
PHOTOGRAPHIC PROCESSES [Communicated to him from abroad by Pierre
Alphonse Attout, called Tailfer, and John Clayton, both of Paris, France.]
"
Waterhouses experiments in the year 1876 have shown the influence of the
introduction of coloring matters into the collodion film of photographs. He found
that Eosine (tetra-brominised phtaléine, a substance discovered by Bayer of
Strasbourg) possessed in a high degree these photogenic properties. Upon these
facts Messrs Ducos du Hauron, and Cros have established their heliochromic process.
The practical results of this process have however hitherto not been so successful
as anticipated. Mr. Sarrault, without pretending to solve the difficult problem of
direct photography in colors, has recently occupied himself simply with reproducing
by means of Eosine the relative values of colors, but in limiting his experiments
to the collodion process, which process is however at present almost universally
replaced by the gelatino-bromide process.
The present invention relates to the application of Eosine to the said gelatino-
bromide process. The difficulty experienced in this application arises from the fact
that Eosine gives no result unless it is introduced with ammonia as a vehicle, and
it is the combined use of ammonia with Eosine that forms the essential feature of
the present improved process.
According to the present invention the gelatino-bromide process of photography
is carried out by two different methods, according as it is desired to prepare the

page_text: gelatino-bromide or to use plates already prepared. In the first case Eosine, by
preference previously dissolved in ammonia, is poured into the emulsion of gelatino-
bromide of silver at the moment of its formation. The proportion of Eosine
employed is about one part by weight to one hundred parts of the compound.
The Eosinised emulsion is spread as usual over the glass plate and after exposure
to the light it is treated in the usual manner for the development and fixing of the
picture.
When gelatino-bromide plates already prepared are available, it is sufficient to
pour over the dry film the ammoniacal solution of Eosine to which alcohol is added.
The plate is then washed, without fear of the removal of the Eusine, which becomes
immediately associated with the gelatino-bromide.
This improved eosinated gelatino-bromide process produces very satisfactory
results. On the photographs produced thereby the relative values of the yellow,
blue and violet colors may be easily distinguisher.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Denton Abel in the Great Seal Patent Office on the
2nd July 1883.
CHARLES DENTON ABEL of N° 28 Southampton Buildings, Chancery Lane, in
the County of Middlesex "IMPROVEMENTS IN THE APPLICATION OF EOSINE IN
PHOTOGRAPHIC PROCESSES" A communication to me from abroad by Pierre
Alphonse Attout, called Tailfer, and John Olayton, both of Paris, France
Waterhouses experiments in the year 1876 have shown the influence of the
introduction of coloring matters into the colludion film of photographs. He found
that Eosine (tetra-brominised phtaléine, a substance discovered by Bayer of
Strasbourg) possessed in a high degree these photogenic properties. Upon these
facts Messrs Ducos du Hauron, and Cros have established their heliochromic process.
The practical results of this process have however hitherto not been so successful
as anticipated. Mr Sarrault, without pretending to solve the difficult problem of
direct photography in colors, has recently occupied himself simply with reproducing
by means of Eosine the relative values of colors, but in limiting his experiments to
the collodion process, which process is however at present almost universally
replaced by the gelatino-bromide process.
The present invention relates to the application of Eosine to the said gelatino-
bromide process. The difficulty experienced in this application arises from the
fact that Eosine gives no result unless it is introduced with ammonia as a vehicle,
and it is the combined use of ammonia with Eosine that forms the essential feature
of the present improved process.
According to the present invention the gelatino-bromide process of photography
is carried out by two different methods, according as it is desired to prepare the
gelatino-bromide or to use plates already prepared. In the former case Eosine, by
preference previously dissolved in ammonia, is poured into the emulsion of gelatino-
bromide of silver at the moment of its formation. The proportion of Eusine
employed is about one part by weight to one hundred parts of the compound. The
cosinised emulsion is spread as usual over the glass plate and after exposure to the
light is treated in the usual manner for the development and fixing of the
picture.
When gelatino-bromide plates already prepared are available, it is sufficient to
pour over the dry film the ammoniacal solution of Eosine to which alcohol is added.
The plate is then washed, without fear of the removal of the Eosine, which becomes
imme liately associated with the gelatino-bromide.
This improved eosinated gelatino-bromide process produces very satisfactory
results. On the photographs produced thereby the relative values of the yellow,
blue and violet colors may be easily distinguished.
Although in what has preceded only Eosine. has been mentioned, it is to be
understood that other acid or saline coloring matters o'tained with the various
Fluoresceines of Resorcine combined with metalloids, Chlorine, Bromine, Iodine
may be included under the same generic term. Also instead of ammonia alone
being applicable as a vehicle for the Eusine, other alkalies may be used for the
purpose.
Having thus described the nature of the said invention, and in what manner the
same is to be performed as communicated to me by my foreign correspondents, I
claim:
In photographic processes of the gelatino-bromine kind, the use of Eosine applied

page_text: with alkali as its solvent and vehicle either in the liquid emulsion or on the dry
layer of a prepared plate.
In Witness whereof I the said Charles Denton Abel have hereunto set my
hand and seal this secondlay of July in the year of our Lord One thousand
eight hundred and eighty three.
CHA. D. ABEL (L.S.)