Clause 3 and clause 4
of the treaty between Niépce and Daguerre.
The physico-chemical
principle of the invention.
by Jacques
Roquencourt.
nous remercions Manuel et Annick
Pourny pour la traduction de ce texte.
Summary: We'll specify the basis of the contract
between Niépce and Daguerre and give a reminder of the
articles restricting the enforcement of the contract. We'll insist on
the physico-chemical principle of the discovery of heliography and
give precise details about the names of the different processes.
We'll prove too that the process using the residue of the Essence of
Lavanda isn't the "Physautotype" , but the physiotipe.
" ...hoping that I won't ask in vain the support of so
many people more able than I to ensure its success... "
Niépce
" ...bound by the agreement which stipulates that my
invention will only be made public when the required perfection has
been attained, this job will be the special charge of my
associate...(Mr. Daguerre) "
(from Niépce to de Curley : on the 18th of
february 1830)
"In 1829 Mr. Daguerre entered into partnership with
Mr.Niépce in order to perfect Mr.Niépce's process."
(Daguerre 1839)
This discovery consists of the spontaneous reproduction
of images obtained in the camera obscura.
Art.3: ... Mr.Niépce will confide to
Mr.Daguerre... the principle on which is based
his discovery...
Art.4: ... Mr.Daguerre commits himself... to keep
silent, as much about the fundamental principle
of the discovery ... and to cooperate as much as he can on
doing the required improvements.
Note.
What I discovered and named "heliography" consists in
spontaneously bringing out the sunlit images received by the camera
obscura, and this with all the shading off black into white.
Basic principle of the
invention.
"Light chemically acts on the bodies either in its
composed or decomposed state. Light is absorbed, combines with these
elements and transmits them new properties. Thus, increasing the natural consistency of some of
these bodies, it even solidifies them and makes them more or less
insoluble, depending on the length and intensity of its action. This
is in a few words the principle of the discovery."
The following text, which is very important and was
published at the beginning of the eighteen twenties, proves that Niépce's physico-chemical
principle (1) was known by the chemists.
"Comments on the solubility of resins and varnishes in
alcohol or in other solvents. After a series of
very simple tests, it's easy to convince ourselves that these
substances are composed of molecules the chemical properties of which
vary depending on their degree of solubility. We have to consider
these substances as a compound of parts : some of which are very
soluble in alcohol at low temperature or even by contact with
alcohol; some other parts which are less soluble require a higher
temperature; and finally some on which the action of air, sunlight or
even heat of infusions leads to some modification which is put in
evidence by their resistance to the action of the spirituous
liquid. However these three parts constitute an homogeneous
whole in the resin.
There is only the dissolution
process which can show them in their real attribute. But
whatever the quantity of liquid which is added to the resinous
residue, it will not be possible to obtain a complete dissolution.
Thus, when we mix up too much matter with alcohol, it
firstly dissolves the most soluble parts and has got very little
dissolution effect on the less soluble ones. The dried parts of the
resin escape from the liquid's action if we only work at moderate
temperature. In this case, the varnish shows only feeble color, but
if it gains in elasticity, it loses consistency and solidity. It's an
advantage to combine these three qualities. We obtain such a
combination by using limited amounts and by operating with much more
care and slowness."
This physico-chemical principle
was the basis of the treaty between Niépce and
Daguerre1.
Niepce and Daguerre's research was continuously
directed by this physico-chemical principle.
We've already and often written that the process of
residue from Essence of Lavanda is not the physautotype !
The photosensitive varnish of the physautotype is
constituted with a compound of petroleum oil residue and of the
residue of the Essence of Lavanda. This same
residue was discovered by Daguerre. In this compound,
the photosensititve part is the petroleum oil
residue. Oil is classified in the family of
bitumen2. The varnish constituted of different proportion
of both residues being not colorated will give an image without
coloration: this was what Daguerre wanted3.
After exposition to the light, the image was obtained
with the successive actions of vapour of sulfuric ether and of liquid
solvent, this method was developped by the diorama's director.
Daguerre discovered the
sensitivity to light of the residue of the Essence of Lavanda
residue.
When Niepce died, our two researchers' work was at this
stage.
Then, Daguerre will bring out an
image thanks to petroleum vapours and this will constitute his contributions to
Niépce's process5.
Concerning the name of the process using the residue of
the Essence of Lavanda, Jean-Louis Marignier, making a pretext of Daguerre's lapse of
memory, attributes the invention of the process to
Niépce as well. Daguerre, after Niepce's death, will mention physiotipe and not physautotype as the
appellation of this process.
Daguerre wrote to Isidore:
"Physiotipe or natural print".
This comes from Phusis = nature and Typos = print.
This demonstrates that Daguerre remembered the
code.
Jean-Louis Marignier's argument
is not acceptable. His argument is
misleading and despoils Daguerre6, and reading the
correspondence demonstrates that Daguerre was
not mistaken and remembered perfectly the code developed by
Nicéphore Niépce. This process only belongs to Daguerre
and to convince ourselves of it, we only need to read Isidore
Niépce's comments on the subject in his lampoon against his
"Dear Associate"4.
"As soon as Mr Daguerre was initiated into the secret
of Niépce's discovery, he kept really busy about it : he
replaced the bitumen of Judea used by my father by the residue from
the distillation of lavender oil; there was an improvement about the
whiteness of the layer which was also more sensitive to the luminous
flux; but, because of the same reason, the destruction of the image
was gradually brought about even in the shade and was prompt and
complete if the prepared metallic plate was exposed to the light.
This improvement could not have a favorable result."
To sum up:
The names of the successive
processes are in direct relationship with the photosensitive product
used:
Heliography = Judea Bitumen =
bitumen = physico-chemical principle of the treaty between
Niépce and Daguerre: invented by Niépce.
Physautotype = residue of
petroleum oil = bitumen residue = physico-chemical principle of the
treaty between Niépce and Daguerre: invented by Niépce
and Daguerre.
Physiotipe = residue of the
Essence of Lavanda = resin residue = physico-chemical principle of
the treaty between Niépce and Daguerre: invented by
Daguerre.
Daguerréotype = silver
iodide = silver salt = physico-chemical principle different from
the physico-chemical principle of the treaty between Niépce
and Daguerre: invented by Daguerre.
As we've already written2, the sensitivity
of the varnish and the visibility of the image will only depend on
the compounds which constitute the varnish.
After exposition to full daylight, the plate is dipped
in a liquid solvent, the image is stripped bare, the residue which
was not exposed to the daylight is dissolved.
When exposed to the vapours of petroleum oil, the image
is not stripped but developed because, in this case, the molecular
change (chaining of carbon atoms) of the residue, more or less
exposed, will be put in evidence by the vapours of petroleum oil.
The principle is identical in the Daguerréotype:
the vapours of mercury brings out, in the same way, the image
according to the exposure to light of the silver iodide.
Notes:
1- Since Isidore's pamphlet and the polemic cleverly carried on
by the family (4), there is no choice but to accept that one doesn't
know how to read a contract!
-We've already mentioned that in the annals of the
"Société L J M Daguerre" published in 1989.
-See our writings contesting the different methods used todistort the
truth.
2- Daguerre and optics by J.Roquencourt in Etudes
photographiques n°5- 1998, notes 3 and 20 (Société
française de photographie).
3- See Daguerre's comment in his opuscule on the colour of the
process of Niépce. (page 39 in "edition Giroux")
4- It's possible that for Jean-Louis Marignier, Isidore can't
remember either!
This pamphlet was reprinted in 1972 &endash;not for sale to the
general public- with a circulation of 1000 by the company
OFMI-GARAMONT*, with the contribution of André Jammes and
Janine Niépce. In it, you can find the photographs of the
first iris diaphragm, naturally attributed to Niépce, the
chamber with bellows which is nothing but the bellows of the
"Pyréolophore" as well as the "laid table" which is not by
Nicéphore. (We'll get back to that point later).
Jean Dereck, by way of warning, acknowledges that "the text may
suffer from a content and a tone more polemical than historical, no
doubt, (he writes), but we thought it was of the greatest interest to
remember the precariousness of Niépce's means and that he had
his share of all kinds of traps, and thus, specifying the respective
duties which the inventor respectedÉ. If this small book somewhat
contributes to the acknowledgement and fame of one of the most
essential French invention, we'll have achieved our aim."
In his introduction, Jean Dereck quotes from Victor Hugo:
"Loving is half way to believing" and finishes by specifying that
this text has been republished as a tribute to Niepce.
Jean Dereck is dead; we would have liked to tell him how his
sincerity has been deceived.
*The firm Ofmi-Garamont has changed its corporate name to
Heidelberg France Company since March 31st, 1998.
5- See the summary written by Daguerre in his opuscule
published by Giroux about the "Modifications made by Daguerre to
Niépce's process".
6- This researcher wrote numerous articles spreading this
mendacious information:
We denounce such a
deception!
- We confess to not understanding this researcher: he may
admire one of these inventors but why does he need to falsify
texts?
- Falsification of texts with the backing of the CNRS and the
Academy of Science!
- JL Marignier stands for the scientific authority of the
"House of Niépce" which is guaranteed by the Academy of
Science!...
We'll point out that his works,
introduced as new, had already been carried out by Niépce de
St Victor.
Arago when tracing the past history of the inventions
of the processes of Niépce and Daguerre, points out that the
use of the residue of lavender as a photosensitive element and
petroleum vapours to bring out the image, are
solely Daguerre's achievements.
One could be surprised that not
one of the historians noticed the contradictions between JL
Marignier's affirmations and all the documented sources.
Commentary by Arago, page 16, in
the opuscule by Daguerre, in Giroux Edition.
" Mr Daguerre imagined a method which is named the
improved Niépce Method. Firstly, he replaced bitumen by the
residue from the distillation of the Essence of Lavanda, because of
its better whiteness and higher sensitivity. This residue was
dissolved in alcohol or ether. The liquid was then allowed to settle
in a very thin and horizontal layer on the metal which left a powdery
and uniform coating after evaporating. This result could not be
obtained by dabbing.
After exposition of the plate (prepared as described
above) in the camera obscura, Mr Daguerre put it horizontally above a
recipient which contained essential oil at room temperature. In these
appropriate conditions, one could appreciate at a glance that the oil
vapours left intact the spherical particulates of the powdery coating
which had received the action of a bright light. Vapours penetrated
more or less the same area of the coating which corresponded to the
halftones in the camera obscura."
Read too this copy of the Academy
of Science Report.
"...because in the last ones, the varnish is only
entirely removed when there are great intensity, and as the halftones
are only produced by more or less thickness of varnish, it's impossible that acid reacts in the same proportion,
which I've already mentioned in a Note I added to Mr Niépce's
process. This drawback hasn't occurred
any more since I've modified the process and replaced the bitumen by
the residue of the Essence of lavender oil, and this residue
dissolved in alcohol and spread on a metal or glass plate
doesn't produce a continuous layer but creates on the surface a
series of small spherical particulates areas of resin which leaves in
between the metal bare. That's why it's possible then for an acid to
etch the plate and that's what I did using fluoric acid on a glass
plate with an image obtained with a camera obscura. To be able to see
the result, I darkened in black the parts of the glass eaten out by
the acid. But this image was very faulty because as the acid reacted
on the entire surface there wasn't enough gradation of tones. This is
an inconvenient which is impossible to avoid using only one acid on a
plate which was not especially prepared for it. These details are by
themselves sufficient to demonstrate that I worked on the etching of
images and that if I didn't speak about it in the description of the
modifications that I brought to Mr Niépce's process, it's
because I judged the results too imperfect. "
Text written in July 1998 and put on internet in
November the 28th 2007.
références :
- premières remarques dans les annales de la
Société L J M Daguerre 1989.
-** article de J B BIOT dans le Journal des Savants en mars et
avril 1839.
-Daguerre et l'optique : J Roquencourt.
Études Photographiques: n°5 1998
(Société Française de Photographie).
-Note sur le portrait de M Huet : J Roquencourt, A
Gunthert.
Études Photographiques: n°6 1999
(Société Française de Photographie).
- L'invention de la photographie: une tragédie (à
paraître)
Summary
May unscrupulous authors respect the intellectual
property and copyrights.
