Improved Means for and Method of Separating Photographic Gelatine Films from their Supports or Bases, and Enlarging the same.
Year: 1894

page_text: Date of Application, 9th Aug., 1894
Complete Specification Left, 1st May, 1895-Accepted, 1st June, 1895
PROVISIONAL SPECIFICATION.
Improved Means for and Method of Separating Photographic
Gelatine Films from their Supports or Bases, and Enlarging
the same.
We, ALBERT JOHN EVES HILL, Manager of The Cresco-fylma Company,
Palmer Crescent, Kingston-on-Thames, and ALFRED ALLEN BARRATT, Clerk
in Holy Orders, of Cleygate Vicarage, Esher, both in the County of Surrey,
do hereby declare the nature of this invention to be as follows:-
This invention relates to improved means for and method of separating photo-
graphic gelatine films from their supports or bases and enlarging the same.
For the purpose of this invention, we mix together a quantity of citric acid or
other vegetable acid of a like nature and a quantity of an alkaline fluoride, such
as, fluoride of sodium.
The proportion of citric acid employed varies according to the extent of
enlargement required, for instance, if it be desired to enlarge the gelatine to twice
its original size a mixture of the materials in or about the following proportions
will be found suitable :-
VAUGHAN & SON,
Agents for the Applicants.

page_text: If, however, a greater enlargement is required the proportion of citric acid must
be increased, and if it be desired to obtain an enlargement of less area or merely
to remove the film from its support or base the proportion of the acid must be
reduced.
When it is desired to employ the above mixture we dissolve the same in water
in a suitable bath in or about the proportions.
Fluoride of sodium
Citric acid-
Water
-
1 dram
9 drams
7 oz.
Into the solution thus formed the plate, which has been well washed after develop-
ment and fixing in the ordinary manner, is immersed.
The gelatine will in the course of a few minutes be observed to frill and finally
leave the glass. The film is then transferred to a larger dish containing water in
which the larger support is placed. The film expands in this water bath and is
left for a time depending to some extent on the temperature but principally on the
developing agent used. The most suitable agents in developing for this purpose,
are those in which an alkaline carbonate is used as accelerator.
It will be readily understood that circumstances may render it necessary to vary
such proportions, for instance the quantity of water will to some extent depend on
the hardness of gelatine used in the manufacture of the dry plate, the softer the
gelatine the greater should be the quantity of water, but the proportions above
given will be found suitable for most plates.
Though we prefer the use of citric acid as the active enlarging agent, other acids
may be used such as tartaric or acetic acid. In order to compensate for a slight
loss of density caused by expansion of the film, we may add mercuric chloride or
other suitable intensifying medium to the water constituting the cold water bath
referred to above; in proportion varying according to the quality of negative
required, as in ordinary photographic procedure.

page_text: Having now particularly described, and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare what we
claim is
I. Separating photographic gelatine films from their supports, and enlarging the
same, by means of an alkaline fluoride, vegetable acid and water, with or without
an intensifier, substantially as described.
Dated this 23rd day of Anril 1895.
ALBERT JOHN EVES HILL.
ALFRED ALLEN BARRATT.