Improvements in the Production of Slides for Optical Lanterns.
Year: 1898

page_text: Date of Application, 30th Sept., 1898
Complete Specification Left, 30th June, 1899-Accepted, 5th Aug., 1899
PROVISIONAL SPECIFICATION.
Improvements in the Production of Slides for Optical Lanterns.
I, LÉO ERRERA, of 38, Rue de la Loi, Brussels, Belgium, Professor at the
University of Brussels, do hereby declare the nature of this invention to be
as follows:-
My invention relates to improvements in the production of slides for optical
lanterns. In carrying out my invention I print the image with transparent ink
by any suitable process of photographic reproduction on a transparent support.
Such support may be of celluloid, gelatine, collodion, mica, specially prepared
glass, or any other transparent and suitable substance.
In this way the lantern slides are mechanically produced either in black, or
single colours, or in a series of colours, such as the natural colours of the object
which are obtained by successive printings in colours on one and the same
support by means of separate blocks or plates each obtained from a different
negative of the same object, the negatives being respectively made after inter-
posing a coloured or intercepting screen.
Datod tha 20th
1
1000
PHILIP M. JUSTICE,
55 and 50, Chancery Lane, London,
Chartered Patent Agent for the Applicant.
Improvements in the Production of Slides for Optical Lanterns.
I, LEO ERRERA, of 38, Rue de la Loi, Brussels, Belgium, Professor at the
University of Brussels, 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:-
-
My invention relates to improvements in the production of slides for optical
lanterns. In carrying out my invention I print the image with transparent ink
by any suitable process of photographic reproduction on a transparent support.
Such support may be of celluloid, gelatine, collodion, mica, specially prepared
glass, or any other transparent and suitable substance.
In this way the lantern slides are mechanically produced either in black, or
single colours, or in a series of colours, such as the natural colours of the object
which are obtained by successive printings in colours on one and the same
support by means of separate blocks or plates each obtained from a different
[Price 8d1

page_text: negative of the same object, the negatives being respectively made after inter-
posing a coloured or intercepting screen.
The preparation of lantern slides in the case where it is desired to reproduce
the natural colours of objects has heretofore usually been a long and costly
process, though various methods are employed for producing them among which
may mention those suggested by Lippmann, Maxwell, Cros, Ducos de Hauron,
Richard and Ives.
The method I employ of printing the required number of transparent posi-
tives on the same transparent support is rendered possible by the employment
of a support which is at the same time transparent and sufficiently flexible to
enable the mechanical printing to be effected.
As an illustration of one manner of producing a slide in natural colours I give
the following:-
-
A first negative is obtained on a plate or support sensitive to yellow and green
rays, after interposing a colourless solution absorbing the ultra-violet rays (for
example a solution of alkaline nitrate) and a yellow intercepting screen (for
example a solution of ammonium picrate, or a gelatine-film stained with
ammonium pierate). A second negative is obtained on an ordinary plate or
support (which is sufficiently sensitive to blue and violet rays) after interposing
the aforesaid colourless solution and a violet intercepting screen (the latter,
however, not being absolutely necessary). A third negative is obtained on a
plate sensitive to orange and red rays, after interposing the above colourless
solution and an orange-red intercepting screen (for example a solution of eryth-
rosine and aurantia or two gelatine-films respectively stained with cosin and
aurantia).
These three negatives are used for obtaining in some well-known way three
blocks or plates either by photocollography (bichromate-gelatine process) or in
phototype-engraving with the help of a net or mesh ("phototypogravure").
From the plate of negative No. 1 may be obtained a crimson print, from the
plate of negative No. 2, a yellow print; and from the plate of negative No. 3,
à greenish-blue print, all three being made with transparent inks on a single
transparent, smooth and flexible support.
The best support appears to be celluloid or gelatine, though it is possible
also to succeed with collodion, mica, or specially prepared glass.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
'
1. In the production of slides for optical lanterns, printing the image
obtained by a process of photographic reproduction on a transparent and flexible
support in a transparent ink substantially as described.
2. In the production of slides for optical lanterns, printing the image by a
series of successive printings in colours from plates or the like obtained from
negatives, the plates of which are sensitive to certain rays only; on a trans-
parent and flexible support in transparent inks substantially as described.
3. The improved slides for optical lanterns produced substantially in the
manner described.
Dated the 30th day of June 1899.
PHILIP M. JUSTICE,
55 and 56, Chancery Lane, London,
Chartered Patent Agent.