AN IMPROVED METHOD OF PRODUCING PHOTOGRAPHIC IMAGES
Year: 1879

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and
Company, Solicitors of Patents, of 67, Strand, in the City of Westminster,
Civil Engineer, for the Invention of "AN IMPROVED METHOD OF PRODUCING
PHOTOGRAPHIC IMAGES." A communication from abroad by David Nunes
Carvalho and Ernest Marx, both of New York City, United States of
America.
Scaled the 19th December 1879, and dated the 26th June 1879.
PROVISIONAL SPECIFICATION left by the said Herbert John Haddan at
the Office of the Commissioners of Patents on the 26th June 1879.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer. "AN IMPROVED
METHOD OF PRODUCING PHOTOGRAPHIC IMAGES." A communication from abroad
by David Nunes Carvalho and Ernest Marx, both of New York City, United
States of America.
The Invention consists in producing photographic images with short exposure by
diffusing the interior of the studio with reflected rays from a non-actinic power, so
as to increase thereby the direct effect of the reflected rays of the object on the
sensitized plate. Also in producing photographic images on the sensitized plate by
diffusing the interior of the studio with reflected rays of non-actinic power and
increasing the effect of the light on the sensitized plate by giving the sensitive film
of the same a color complementary to that of the reflected raya, Also in producing
photographic images on the sensitized plate by very short exposure by diffusing the
studio with reflected non-actinic rays, and by a covering of an orange-pea-green
color, and increasing the sensitiveness of the plate by using a collodion film of a
violet color complementary to the color of the room. Also in producing photo-
graphic images by very short exposure by diffusing the studio with rays of non-
actinic power, and imparting to the sensitized plate a color complementary to these
rays by employing a collodion and bath of a color complementary to that of the
diffused rays. Also in the application of sensitized plates having a collodion or
other film of violet color. The diffusion of non-actinic rays in the studio can be
obtained by painting the walls orange-pea-green or with any other non-actinic
colour, and the complimentary colour of the collodion and bath by adding thereto
any suitable colouring substance of a violet or other actinic colour.

page_text: .
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Herbert John Haddan in the Great Seal Patent Office on
the 19th December 1879.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer. "AN IMPROVED
METHOD OF PRODUCING PHOTOGRAPHIC IMAGES." A communication from abroad
by David Nunes Carvalho and Ernest Marx, both of New York City, United
States of America.
This Invention relates to an improved method of producing photographic images,
by which the time of exposure is shortened and rendered less annoying to the sitter,
and by which superior negatives and positives are obtained, in which the high
lights are stronger and the shadows softer, and by which, furthermore, less retouching
is required than by the ordinary method in use.
One of the main objects of the photographic art has been to produce with short
exposure a full timed negative. A number of complicated chemical processes have
been devised for this purpose but they have for some reason or other failed to give
satisfaction, and have not worked to advantage.
The object of this Invention is to supply to the photographer a simple but very
effective method by which he is enabled to obtain with the common ordinary appli-
ances and with a very short exposure a superior and full timed negative.
This result the inventors have obtained by the operation of optical means, mainly,
by discarding, in the first place, the hitherto generally adopted blue black or neutral
colors for interior of the photographic galleries, and substituting therefor a color
that reflects rays of non-actinic quality; and, secondly, by employing for the sensi-
tive film or coating of the glass plate collodion or other substratum, of a color
complementary to the predominating color of the surroundings.
The inventors discovered accidentally that by working under a sky-light glazed
with uncolored glass, in a studio, the walls of which had been painted in a brown
color, that it took considerably less time to make a negative than was required in
the same room when the walls were painted with the "orthodox" blue color of
photographic fame. In following up this experience by a series of experiments, the
inventors discovered that by employing colors the reflected rays of which were
supposed to have little or no actinic power, the time of exposure required for full
timed negatives was more and more reduced.
Now, as according to the laws of optics, an opaque body of a certain color, when
exposed to light, absorbs the rays of its complementary color but reflects rays of
the same color, the above experiments led the inventors to suppose that the blue
rays reflected by the common blue color of the studios were instrumental in
retarding instead of accelerating the formation of the picture on the sensitized
plate, owing to the disturbing influence of the reflected blue rays on the rays
reflected from the object to the plate.
Thus, the blue color heretofore used in the rooms, instead of shortening the
exposure, exerted an unfavorable influence and prolonged the time of exposure. By
employing therefore a color, the reflected rays of which are supposed to be actinic,
these rays would exert no disturbing influence on the object to be photographed.
In other words, the rays which are reflected from the object on the sensitized plate
exert their full actinic power thereon and produce, consequently, a better picture in
less time.
It is also well known that the violet and violet indigo rays of the spectrum are
the most actinic, possessing in the highest degree the power by which chemical
changes are produced. A color complementary to violet would consequently reflect
rays of least actinic power, and a paint of such complementary color when used for
the interior of the photographic galeries, instead of exerting a disturbing influence,
would furnish reflected -rays of a non-disturbing character and admit the quicker

page_text: and more perfect development of the image on the sensitized plate owing to the
diminished interference of the reflected rays with the rays thrown from the object
on the sensitized plate. The inventors obtained the complementary color of violet
by mixing Prussian blue and deep chrome in certain proportions, which mixture has
a greenish-orange hue or tint, and resembles somewhat an "orrange-pea-green."
By applying a paint or other covering of this color to the interior of the sky-light
room, excepting the glass, a full timed negative was obtained with a considerable
reduction of exposure as compared to the blue, brown, or other colors therefore
employed.
The good effects of the "orange-pea-green" paint by which the interior walls,
joinerwork, &c., of the skylight room were coated iuduced the inventors to continue
their experiments with a view to a still further shortening of the time of exposure.
The inventors employed variously colored collodions and baths, and found that by
using a collodion and silver bath of a violet color complementary to the "orange-
pea-green " of the room that the plate became more sensitive to the light. Tho
conjunction of the complementary colors of the walls, background, screens, etc.,
and of the sensitized plate, neutralised the disturbing influences heretofore ex-
perienced, and accelerated the chemical action of the rays reflected from the object
to be photographed in such a manner that under favorable circumstances a full timed
negative was obtained by an instantaneous exposure merely, while under less
favorable circunstances an exposure of a few seconds only was required. This
favorable result, which is obtained simply by optical means, becomes more apparent
when in contradistinction to the complementary violet a collodion and bath of the
color of the room, viz., "orange-pea-green," is used, in which case, with the longest
exposure and under most favorable conditions, only a dim outline of the object
photographed was produced, no shadows whatever appearing and only slight
indications on the light side.
Besides the reduction in the time of exposure it was found that the use of orange-
pea-green color for the interior of the studio was less trying to the eyes of the
sitter, which is readily explained by the fact that it contains green, the restoring
color. The eye rests upon the photographic color with a feeling of satisfaction and
renders thus the sitting less objectionable than it was hitherto with the blue or
gray color of the interior.
The absence of disturbing influence, such as cross light, dense shadows, etc.,
simplifies the work of the operator and enables him to produce with almost instan-
taneous exposure superior negatives in which the high lights are more positive and
the shadows softer.
The image is developed in the ordinary manner and the negative thus obtained
retains its violet color, so that the silverpaper used for printing purposes is more
quickly affected by the light, and thereby a main desideratum of photographers,
viz., a shortening of exposure and a saving of time in printing obtained by cheap
and exceedingly simple means.
CLAIMS.
1. The method herein described of producing photographic images with short
exposure, consisting in diffusing the interior of the studio with reflected rays of
non-actinic power, so as to increase thereby the direct effect of the reflected rays of
the object on the sensitized plate, substantially as set forth.
2. The method herein described of producing photographic images on the sensi-
tized plate by diffusing the interior of the studio with the reflected rays of non-
actinic power, and increasing the effect of the light on the sensitized plate by giving
the sensitive film of the same a color complementary to that of the reflected rays,
substantially as described.
3. The method herein described of producing photographic images on the
sensitized plate by very short exposure, consisting in diffusing the studio with
reflected non-actinic rays by using a covering of an orange-pea-green color, and

page_text: complementary to the color of the room, substantially as and for the purpose
specified.
4. The method herein described of producing photographic images by very short
exposure, consisting in diffusing the studio with rays of non-actinic power, and
imparting to the sensitized plate a color complementary to these rays by employing
a collodion and bath of a color complementary to that of the diffused rays,
substantially as set forth.
5. In the art of producing photographic images, the employment of sensitized
plates having a collodion or other film of violet color, substantially as set forth.
In witness whereof, I, the said Herbert John Haddan, have hereunto set 1
my hand and seal, this Fifteenth day of December, A.D. 1879.
T HADDAN