Improvements in the Manufacture of Sensitive Plates and Films for Photographic Purposes.
Year: 1894

page_text: Date of Application, 5th Mar., 1894
Complete Specification Left, 5th Dec., 1894-Accepted, 5th Jan., 1895
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Sensitive Plates and Films for
Photographic Purposes.
I, CHARLES EDWIN PETTITT of 46 Fleet Street Torquay in the County of
Devon, Photographer, do hereby declare the nature of this invention to be as
follows:
--
My invention has reference to the manufacture of sensitive plates and films
for photographic purposes and its object is to prevent or diminish balation (local
over-exposure) and solarization (reversal of the image by over exposure).
The invention consists in the interposition between the sensitive emulsion and
the glass plate, film or other support, of a substratum or coating containing
a fluorescent substance such for example as cinchonia or quinine which is non-
actinic because although colorless it possesses the power of lowering the
refrangibility of certain rays of the spectrum. Substances possessing this power
are generally termed fluorescent.
In carrying out the invention I coat the plate or film with a non-sensitive sub-
stratum or coating of gelatine, collodion, albumen or other suitable vehicle with
which cinchonia or other fluorescent substance has been thoroughly incorporated
so as to render the substratum or coating non-actinic. The vehicle preferably
used for the purpose is gelatine of the same physical character as that employed
in the preparation of the sensitive emulsion used on the plate or film. When
this non-actinic, non-sensitive substratum has become thoroughly set and dry I
coat it with an emulsion of any required sensitiveness.
After the exposure of the plate the non-actinic property of the fluorescent
substance is destroyed by the subsequent processes of development and fixation ;
also the simple action of washing removes the substance from the substratum.
Dated this 5th day of March 1894.
J. C. MEWBURN,
55 and 56, Chancery Lane, London, Chartered Patent Agent.
Improvements in the Manufacture of Sensitive Plates and Films for
Photographic Purposes.
I, FLORENCE ALICE PETTITT of 46 Fleet Street, Torquay in the County of
Devon, Widow and Administratrix of Charles Edwin Pettitt late of 46 Fleet
Street, Torquay in the County of Devon, Photographer, deceased, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
This invention has reference to the manufacture of sensitive plates and films
for photographic purposes and its object is to prevent or diminish halation (local
over-exposure) and solarization (reversal of the image by over-exposure).

page_text: The invention consists in the interposition between the sensitive emulsion and
'the glass plate, film or other support, of a substratum or coating containing a
fluorescent substance such for example as quinine or cinchonia, which is
non-actinic, because although colorless it possesses the power of lowering the
refrangibility of certain rays of the spectrum. Substances possessing this power
are generally termed fluorescent.
In carrying out the invention the plate or film is coated with a non-sensitive
substratum or coating of gelatine, collodion, albumen or other suitable vehicle with
which quinine or other fluorescent substance has been thoroughly incorporated,
so as to render the substratum or coating' non-actinic. The vehicle preferably
used for the purpose is gelatine of the same physical character as that employed
in the preparation of the sensitive emulsion used on the plate or film. When this
non-actinic, non-sensitive substratum has become thoroughly set and dry it is-
coated with an emulsion of any required sensitiveness.
After the exposure of the plate the non-actinic property of the fluorescent
substance is destroyed by the subsequent processes of development and fixation ;
also the simple action of washing removes the substance from the substratum.
The manner in which the non-actinic, non-sensitive substratum or coating is
preferably prepared is as follows:-
Dissolve one part of sulphate of quinine (medicinal quinine) in ten parts of
water or spirit which has been acidulated with sulphuric acid. Then in this
solution dissolve gelatine by the application of heat, the proportion of gelatine
being more or less according to the thickness of the coating it is desired to
obtain, the glass plate or film is coated with this gelatine and quinine solution,
and when this has become dry or set it is coated with the sensitive emulsion.
Having now particularly described and ascertained the nature of the said inven-
.tion and in what manner the same is to be performed, I declare that what I
claim is :-
:―
1. In the manufacture of sensitive plates or films, the interposition between
the sensitive emulsion and the plate or other support of a colorless non-actinic,
non-sensitive substratum, substantially as and for the purposes described.
2. The photographic plate or film substantially as described, in which a
substratum containing quinine or cinchonia is interposed between the sensitive
emulsion and the plate or other support.
Dated this 5th day of December 1894.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Patent Agents.