Improvements relating to the Production of Photographs on Silk.
Year: 1899

page_text: Date of Application, 20th Aug
4000
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Complete Specification Left, 28th May, 1900-Accepted, 28th July, 1900
Complete Specification Left, 28th May, 1900-Accepted, 28th July, 1900
PROVISIONAL SPECIFICATION.
Improvements relating to the Production of Photographs on Silk.
FRANK JAMES FARRELL, of 37, Crown Road, Great Yarmouth, in the County
of Norfolk, Technical Chemist, and ERNEST BENTZ, of 5, Demesne Road, Whalley
Range, Manchester, in the County of Lancaster, Technical Chemist, do hereby
declare the nature of this invention to be as follows:-
This invention refers to a new method for producing photographs upon silk
fabrics.
Silk is immersed in a dilute solution of nitrous acid, with the addition of
hydrochloric acid, sulphuric acid, or other suitable acid, for about 12 hours at
the ordinary temperature, the operation being conducted in the dark.
The silk thus treated becomes bright yellow in colour, being converted, it would
appear, into a diazo compound, (chloride sulphate or other compound, correspond-
ing with the acid employed). The silk is then rinsed in water and dried in the
dark.
We find that the silk thus prepared is very sensitive to light, a few seconds in
direct sunlight or a few minutes in diffused sunlight sufficing to change the bright
yellow colour to a very pale buff.
Before exposure to light, the silk coloured yellow in the manner above described
possesses the property of combining with phenols, such as, phenol, resorcinol,
alpha naphthol, beta naphthol, and their sulpho and carboxy derivatives in
alkaline solutions, and with aromatic amido compounds, aniline, metaphenylene
diamine, alpha naphtylamine, betanaphtylamine etc. in acid solutions, forming
coloured compounds.
After exposure to light, the silk which has been treated in the manner described
with nitrous acid, loses this property, the yellow silk compound becoming chemi-
cally changed by the action of the light.
We find that silk treated with nitrous acid according to the method above
stated, after being placed under a photographic positive, and thus exposed to light,
when it is treated with a phenol in alkaline solution or an aromatic amido com-
pound in acid solution gives a photograph similar to that on the plate under which
the silk has been exposed, that is to say, a positive print of the picture on the
positive is obtained.
In the same way exposure under a photographic negative, we find, produces a
negative print of the picture upon the silk.
The colours produced by development as above described, may be modified by
after treatment with metallic salts, as described in the Provisional Specification
of Letters Patent No. 24628 of the year 1896. For example, development with
beta naphthol in alkaline solution gives a bright red shade, which when treated
with solutions of cobalt salts changes to a maroon shade.
Again, development with resorcinol in alkaline solution gives a golden yellow
shade which when treated with iron compounds changes to a deep brown or olive.
The modified colours thus obtained are in general extremely fast.

page_text: The colours obtained by development with aromatic amido compounds when
treated with nitrous acid for a short time, and subsequently developed with
phenols, naphthols, etc. in alkaline solution, or aromatic amido compounds in
acid solution, give new coloured compounds, which again can be further modified
by treatment with certain metallic salts.
For example, the colour obtained by the development of the treated silk with
alphanaphthylamine in hydrochloric acid solution is a golden yellow. This when
it is acted upon by nitrous acid and then treated with sodium amido naphthol
disulphonate (1:8:3:6) gives a greenish slate colour; or, when it is acted upon
by nitrous acid and then treated with beta naphthol in alkaline solution it gives
a purple colour. This latter on treatment with an iron salt, for instance ferrous
sulphate, changes to an almost black colour.
When the silk which has been acted upon as described with nitrous acid, is
exposed to light, it does not pass directly from what we assume to be the state of
diazo compound to the state of a compound which no longer possesses affinity for
phenols or amido compounds, but it goes through an intermediate stage, a nitroso
compound, we assume, being formed.
This intermediate compound is obtained by exposing to light the yellow coloured
silk compound described, for a much shorter time than is necessary to render it
chemically inactive with phenols and amido compounds.
When silk thus exposed for a very short time to sunlight is placed in alkaline
solutions (caustic soda, potash, ammonia, etc.) a brown colour is produced.
As what we assume to be the diazo compound of silk does not change colour
very much under the action of alkalis, this property can be utilized for producing
positive prints from photographic negatives.
Thus, we expose the yellow coloured silk compound obtained by treating silk
with nitrous acid in the manner described, under a negative for a sufficient length
of time to bring the yellow silk compound in the parts where the light has access,
to the intermediate (or nitroso) stage, then we treat with an alkali the resulting
compound of the silk and we obtain a dark brown positive print on a yellow
ground.
We utilize the same property in printing from photographic positives in
the following way:-We expose the silk treated with nitrous acid in the manner
described, under a photographic positive, the compound in the exposed places on
the treated silk (that is, where the sunlight has penetrated) becoming changed
into an inactive compound, while the unexposed portions of the silk (that is,
where the sunlight has not had access) are still in a chemically active state.
We then remove the photographic positive and we expose the whole surface of
the silk to light for a short time; the inactive parts remain unchanged, but the
active portions are changed into the above mentioned intermediate compound
which we then convert into the brown coloured compound by the action of an
alkali as before stated.
Dated this 26th day of August 1899.
COMPLETE SPECIFICATION.
Improvements relating to the Production of Photographs on Silk.
We, FRANK JAMES FARRELL, 37, Crown Road, Gt. Yarmouth, and ERNEST BENTZ,
5, Demesne Road, Whalley Range, Manchester, do hereby declare the nature of

page_text: this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
1
This invention refers to improvements relating to the production of photo-
graphs upon silk fabrics. Silk is immersed in a dilute solution of nitrous acid with
the addition of hydrochloric acid, sulphuric, or other suitable acid, for about
12 hours at the ordinary temperature or for a shorter period at a sufficiently high
temperature, the operation being conducted in the dark.
The silk thus treated becomes bright yellow in colour, being converted it would
appear into a diazo compound (chloride, sulphate or other compound correspond-
ing with the acid employed). The silk is then rinsed in water and dried in the
dark. We find that the silk thus prepared is very sensitive to light, a few seconds
in direct sunlight or a few minutes in difused sunlight sufficing to change the
bright yellow colour to a very pale buff. Before exposure to light the silk
coloured yellow in the manner above described possesses the property of combining
with phenols, such as phenol, resorcinol, alpha-naphthol, beta-naphthol, and their
sulpho and carboxy derivatives in alkaline solutions, and with aromatic amido
compounds, aniline, meta phenylene diamine, alpha naphtylamine, beta naphty-
lamine &c. in acid solutions, forming coloured compounds; after exposure to
light the silk which has been treated in the manner described with nitrous acid
loses this property, the yellow silk compound becoming chemically changed by
the action of the light. We find that silk treated with nitrous acid according to
the process above stated, after being placed under a photographic positive, and
thus exposed to light, when it is treated with a phenol in alkaline solution or an
aromatic amido compound in acid solution gives a photograph similar to that on
the plates under which the silk has been exposed, that is to say, a positive print
of the picture on the positive is obtained. In the same way exposure under a
photographic negative we find produces a negative print of the picture upon the
silk. The colours produced by development as above described may be modified
by after treatment with metallic salts. For example, development with beta-
napthol in alkaline solution gives a bright red shade, which when treated with
solutions of cobalt salts changes to a maroon shade. Again development with
resorcinol in alkaline solution gives a bright golden yellow shade which when
treated with iron compounds changes to a deep brown or olive.
Modified shades are also produced by treating with nickel, chromium, copper
and many other salts. The modified colours thus obtained are in general
extremely fast.
The colours obtained by development with aromatic amido compounds, when
treated with nitrous acid for a short time and subsequently developed with phenols
napthols &c., in alkaline solution or aromatic amido compounds in acid solution
give new coloured compounds which again can be further modified by treatment
with certain metallic salts. For example, the colour obtained by the development
of the treated silk, with alpha napthylamine in hydrochloric acid solution is a
golden yellow. This when it is acted upon by nitrous acid and then treated with
sodium amido naphthol disulphonate (1:8:3:6:) gives a greenish slate or what
may be termed a greenish blue colour, or when it is acted upon by nitrous acid,
and then treated with beta-napthol in alkaline solution, it gives a purple colour.
This latter on treatment with an iron salt for instance ferrous sulphate, changes
to an almost black colour.
When the silk which has been acted upon as described with nitrous acid, is
exposed to light, it does not pass directly from what we assume to be the state
of a diazo compound, to the state of a compound which no longer possesses
affinity for phenols or amido compounds, but it goes through an intermediate
stage, a nitroso compound we assume being formed.
This intermediate compound is obtained by exposing to light the yellow coloured
silk compound described for a much shorter time than is necessary to render it
chemically inactive with phenols and amido compounds.

page_text: When silk thus exposed for a very short time to sunlight is placed in alkaline
solution (caustic soda, potash, ammonia &c.) a brown colour is produced. As
what we assume to be the diazo compound of silk does not change colour very
much under the action of alkalies, this property can be utilised for producing
positive prints from photographic negatives. Thus, we expose the yellow coloured
silk compound obtained by treating silk with nitrous acid in the manner described
under a negative for a sufficient length of time to bring the yellow silk compound
in the parts where the light has access to the intermediate (or nitroso) stage, then
we treat with an alkali the resulting compound of silk, and we obtain a dark
brown positive print on a yellow ground.
We utilise the same property in printing from photographic positives in the
following way:-We expose the silk treated with nitrous acid in the manner
described under a photographic positive, the compound in the exposed places on
the treated silk (that is where the sunlight has penetrated) becoming changed
into an inactive compound, while the unexposed portions of the silk (that is
where the sunlight has not had access) are still in a chemically active state.
then remove the photographic positive and we expose the whole surface of the
silk to light for a short time; the inactive parts remain unchanged but the active
portions are changed into the above mentioned intermediate compound which we
then convert into the brown coloured compound by the action of an alkali as
before stated.
We
It will be seen that the essential feature of the invention consists in the
treatment of silk or fabric with the diluted solution of nitrous acid with the
addition of hydrochloric acid, sulphuric acid, or other suitable acid, the operation
being conducted in the absence of light for the purpose of rendering the silk
sensitive to light.
said
Having now particularly described and ascertained the nature of our
invention, and in what manner the same is to be performed, we declare that what
we claim is: -
1. The improved process for rendering silk sensitive to light as and for the
purpose set forth.
2. The treatment of silk with nitrous acid in combination with other suitable
acids in the absence of light for the purpose of rendering the silk or fabric
sensitive to light so that according to the length of exposure to light and the
re-agents or chemical bodies employed, the required tints or colours may be
obtained for the purpose of giving what is known in photography as a positive
or negative effect substantially as described and set forth.
3. The treatment of silk or fabric as set forth, for the purpose of rendering it
sensitive to the action of light rays, which action produces a chemical change in
the silk or fabric compound, which change determines the action on or combination
therewith of re-agents or chemical substances upon the silk or fabric compound,
for the purpose of variation of colour as set forth and described.
1000