Improvements in Processes of Making Transparent Photographs on Glass.
Year: 1893

page_text: Date of Application, 28th Mar., 1893
Complete Specification Left, 27th Dec., 1893-Accepted, 10th Feb., 1894
PROVISIONAL SPECIFICATION.
Improvements in Processes of Making Transparent Photographs
on Glass.
I, CHARLES ARTHUR ALLISON, of 52 Chancery Lane, London, in the County
of Middlesex, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by Francis Bernhard Forster and
George Gardner Rockwood, both of 1440 Broadway, in the City, County and State
of New York, United States of America, Photographers), to be as follows:-
This improved process consists in first printing a positive image from a photo-
graphic negative in the usual manner, in a metallic oxide, such as the oxide of
copper, iron or gold, upon a medium, such as glass or paper, which has been
surfaced with a mixture of the material constituting the sensitive film and the
metallic oxide; then in the well-known manner transferring said print to and in the
usual way developing it upon a temporary support, such as a plate of glass; then
transferring said developed print to a base or plate of transparent glass and
rendering it insoluble thereon by the application thereto of a solution of chrome-
alum, or its equivalent; then coating the print with a vitreous flux which fuses at
a lower degree of heat than the melting-point of the glass base; and finally
subjecting the base and the print and flux thereon to a degree of heat to fuse
the flux.
A vitreous flux which fuses at about 600° to 700° Fahrenheit, is desirable.
Such a flux may be composed of 200 parts of yellow oxide of lead, 20 parts of
borax, and 89 parts of quartz sand.
Dated this 28th day of March 1893.
ALLISON BROS.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Processes of Making Transparent Photographs
on Glass.
1, CHARLES ARTHUR ALLISON, of 52 Chancery Lane, London, in the County
of Middlesex, Patent Agent, do hereby declare the nature of this invention
(which has been communicated to me from abroad by Francis Bernhard Forster,
of 1440 Broadway, in the City, County and State of New York, United States of
America, Photographer, and George Gardner Rockwood, of 1440 Broadway, in
the City, County and State of New York, United States of America, Photographer)
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
In carrying out this invention, the sensitive medium upon which the photographic
picture is printed from the negative is surfaced with a mixture of gelatine and a
metallic oxide, such as oxide of copper, iron or gold, and this mixture is dried on
the medium, which may be glass or paper, in a dark room. This prepared medium
is then exposed to light under a photographic negative in the usual manner. When
the picture is thus printed on the said medium, the surface of the film bearing the
print is coated with collodion. The print is now transferred to a temporary support,
such as gelatinized paper; which is accomplished by causing the paper to adhere
to the film and then withdrawing the paper carrying the film with it from the

page_text: glass.
manner.
The print on the temporary support is then developed in the usual
The film-picture, in the metallic oxide, is then transferred from the temporary
support to the surface of the permanent glass base. This leaves the picture, in the
metallic oxide, on the glass. The collodion is now washed away by a flow of
ether, and the picture-film is rendered insoluble on the glass by the application of
a solution of chrome-alum, and the plate is then dried.
The picture-film on the glass is then coated with a vitreous flux which fuses at a
lower temperature than the melting-point of the glass-base; and such a flux may
be composed of two hundred (200) parts of yellow oxide of lead, twenty (20) parts
of borax, and eighty-nine parts of quartz sand. These materials are pulverized
and mixed, and in a fine powder are dusted over the film.
The glass plate bearing the film and flux is then subjected, in a suitable kiln, to
a degree of heat, say between six hundred (600) and seven hundred (700) degrees,
Fahrenheit, to fuse the flux, which acts to vitrify the metallic oxide upon the glass
base, and to cover the picture with a transparent, vitreous coating; so that the
picture is permanently, unchangeably and indestructibly affixed to and in the
surface of the glass base, and is visible by both transmitted and reflected light.
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:
The process of making transparent photographic pictures which consists in
printing the positive image, in a metallic oxide, from the negative upon a medium
which has been surfaced with a mixture of the materials constituting the sensitive
film and said metallic oxide; then transferring said print, in said metallic oxide,
to, and developing it upon, a temporary support then transferring said developed
print to, and rendering it insoluble upon, the surface of a transparent glass plate;
then coating said print with a vitreous flux of the character stated and which fuses
at about the temperature specified; and subjecting the glass plate, bearing the
print and its flux,. to a degree of heat to fuse the flux, substantially as set forth.
Dated this 27th day of December 1893.
ALLISON BROS.,
Agents for the Applicant.