For two hundred years, scientists have defended the legacy of Niépce.

BIENNALE DI SENIGALLIA

In his talk, Jean Dhombres emphasized Niépce’s methodical and scientific mindset, highlighting how carefully and systematically Niépce approached his experiments and discoveries.

Jean Dhombres started his conference by reading the “Lettre de Nicéphore Niépce à Alexandre du Bard de Curley, 25 octobre 1825” (video online)

Labor improbus omnia vincit. I have personally verified this adage regarding my research: I have finally succeeded in correctly engraving on copper, and I am about to have two or three copies of engravings printed based on the improvements to my processes. If the proofs turn out well, I will have the pleasure of sending you some. I regret being still behind schedule for the views: my improvements came a little too late in the season; but I am confident of future success, and that is already a great deal. I have also commissioned a meniscus prism, which I greatly need to give my research the full breadth it is capable of achieving.

After Chevalier Ignace Joseph de Claussin (below), after Dirk van der Stoop (second below), after Philips Wouwerman, A Boy talking a Horse to Drink, 1651

Paper print from an Heliograph on copper plate,100×147 mm, August 1825 Printed in Dijon circa November-December 1825. Provenance this print, mentioned in the 25 october letter, given to Alexandre Dubard de Curley, 12 March 1826, described by an old books-dealer from Brussels, Tristan Schwilden, then Collection André Jammes, then Sotheby’s auction, 21 March 2002, now Bibliothèque Nationale.

Note : In the chronology of Nicéphore Niépce’s work, the first mentions of experiments with bitumen of Judea on copper date back to June 1824. At that time, Nicéphore had succeeded in engraving on this medium images obtained with the camera obscura:

“With my current composition, I have also succeeded in engraving on red copper as well as on stone—a result I had previously achieved only very imperfectly with my other process” (letter from Nicéphore to Claude, June 13, 1824, ASR).

In a previous letter (preserved) sent to his cousin de Curley in June 1825, Nicéphore revealed that he was eagerly awaiting copper plates to carry out new experiments (June 5, 1825, BNF).

In July 1825, Nicéphore contacted the engraver Lemaître. Through M. de Champmartin, he sent him “two small copper plates, varnished and ready to receive the action of acid.”

However, this attempt ended in failure, as the layer of varnish was not sufficiently resistant (cf. Letter from Nicéphore to Lemaître, January 17, 1827, ASR).

In a previous letter (preserved) sent to his cousin de Curley in June 1825, Nicéphore revealed that he was eagerly awaiting copper plates to carry out new experiments (June 5, 1825, BNF).

In July 1825, Nicéphore contacted the engraver Lemaître. Through M. de Champmartin, he sent him “two small copper plates, varnished and ready to receive the action of acid.”

However, this attempt ended in failure, as the layer of varnish was not sufficiently resistant (cf. Letter from Nicéphore to Lemaître, January 17, 1827, ASR). Nevertheless, Nicéphore persevered and, in August 1825, found a better way to engrave his copper plates: “I [can] repeat the operation, that is to say, paint and engrave alternately, until I have obtained the depth sufficient for the printing ink” (cf. Letter from Nicéphore to Claude, August 7, 1825, ASR).

Satisfied with this improvement (alternating stripping and chemical engraving), he decided to approach a printer in Dijon in the fall of 1825 to have some engraved plates printed. He reported the results of this effort to his cousin de Curley in his letter of January 14, 1826: “dear Cousin, I had a few proofs of my copper engravings printed in Dijon; but, either through my fault or that of the printer, these proofs lack the desired sharpness and correction.”

Dhombres also drew attention to one of Niépce’s greatest contemporaries, Joseph Fourier, underlining the intellectual environment of the time. As civilian governor of Egypt (1798–1801), Fourier launched the Institut d’Égypte. Later, he directed large-scale engineering projects, like draining the swamps of Grenoble. And as a scientist, he wrote the book that changed how we think about heat, introducing thermodynamics. Three bold moves—science in action, shaping the world Niépce lived in.

Fourier’s scientific vision helped define the intellectual landscape of Niépce’s lifetime.

He spoke about the crucial role played by scientists during the years of the French Revolution and the Empire, showing how the scientific community was deeply involved in the political and social changes of the era. Dhombres insisted that the scientific spirit and the drive for innovation were not isolated from society, but rather, were fundamental to the transformations happening in France at the turn of the nineteenth century.

Now, to illustrate this scientific spirit, Dhombres told how, as a series editor at Belin, he once received the manuscript by Jean-Louis Marignier. The manuscript described, in extraordinary detail and with remarkable precision and empiricism, Marignier’s colossal work to reconstruct, step by step, every single experiment carried out by Nicéphore Niépce. The sheer scale and rigor of this work actually intimidated the publisher, and Dhombres had to fight to get it published—even though the series itself was called “A Scientist, An Era.”

So here is one of the mysteries resolved: how did the most fundamental book for anyone interested in the invention of photography—that is, the book by Jean-Louis Marignier—finally get published?

Marignier’s research is legendary for its thoroughness. He not only retraced Niépce’s technical and chemical processes, but also managed to reproduce them in the laboratory, reviving techniques that had been lost since the 1820s. His book, L’invention de la photographie (Belin, 1999), remains a reference, even though it is now out of print.

What is less well known about Marignier—but is present in the exhibition—is the scientific article that explains, at the atomic level, how the invention of photography was even possible.

It took more than one and a half centuries to understand and explain what Niépce invented!

Background on Silver Cluster Nuclearity and Photographic Chemistry:
The idea that the smallest metallic aggregates (clusters) of silver have a specific reduction potential—more negative than that of bulk silver, and dependent on the number of atoms (n) in the cluster—was first introduced by Delcourt and Belloni in 1973. This insight is fundamental for understanding the chemistry behind silver-based photography.
Mechanism of the Photographic Process:

Photons strike the crystals of silver halide (like AgBr), ejecting an electron from the bromide ion (Br⁻) (exposure to light) and generating electron-hole pairs in the crystal lattice. The photo-generated electrons reduce silver ions (Ag⁺) to neutral silver atoms (Ag⁰), which then cluster together.

Only those silver clusters that exceed a critical size—called the critical nuclearity (n_c, typically 3–5 atoms)—are stable enough to survive oxidation by the positive holes left in the lattice after electron ejection (formation of the latent image).These supercritical clusters act as “seeds” for the development process.

During chemical development, the supercritical silver clusters—thanks to their specific structure and electronic energy — accept electrons from the developer and aattract Ag⁺ ions to their surface. In this way, the clusters catalyze the reduction of Ag⁺ ions at their surface, growing into larger, visible metallic silver nanoparticles.

As they grow, their catalytic properties intensify. This autocatalytic process continues until one key resource is exhausted or removed—either the developer’s electrons or nearby Ag⁺ ions.

Each supercritical cluster catalyzes the reduction of millions of silver ions, yielding a visible image with up to 10⁸-fold amplification. The image forms as these metallic silver grains are deposited throughout the emulsion, where areas of higher silver density appear darker and contribute to the image’s contrast as it emerges.

The research by Marignier, Belloni and Mostafavi throughout the 1980s and 1990s consolidated this model. Their work showed that the stability and reactivity of silver clusters are strongly influenced by solvation and the presence of ligands (like gelatin or polymers) in the emulsion, and that the kinetics of cluster coalescence compete with oxidation, directly impacting image formation.

Pulse radiolysis studies confirmed that ultrafast reduction of Ag⁺ ions is driven by pre-solvated electrons, especially in acidic environments, and that cationic clusters (like Ag₂⁺) are key intermediates in cluster growth.

The pioneering work of Belloni, Mostafavi, Marignier & Amblard —over 150 years after the invention of photography—finally provided the thermodynamic and kinetic framework to explain why isolated silver atoms are unstable, but clusters with n > n_c persist and catalyze further reduction, and how the reduction potential’s dependence on cluster nuclearity enables the catalytic amplification essential for photographic development.

These principles remain fundamental for understanding the invention and functioning of silver-based photography, highlighting the unique photochemical properties of silver clusters.

So let’s ask the uncomfortable question that troubles commentators and historians alike:

Can you really engage with the history of science without even a basic education in science, or any hands-on scientific experience?

The lecture was followed by a guided tour of the exhibition “Les Mystères de la Photographie,” which offered further context and visual insight into the birth and early development of photography.

Let’s conclude with three special cards dedicated to the scientific approach leading to the invention of Photography.

MYT-8- Della Porta, Keplero e la camera oscura, ca. 1604. Johannes Kepler, astronomo imperiale a Praga, pubblica nel 1604 l’Ad Vitellionem Paralipomena, fondamento dell’ottica moderna. Vi spiega il funzionamento geometrico della camera obscura, collegandolo alla visione umana. I suoi studi si basano sulle osservazioni di Giovan Battista Della Porta, che già nel 1589 aveva descritto una camera oscura dotata di lente nella Magia Naturalis.

Keplero supera l’approccio empirico di Della Porta e ne formalizza le intuizioni con rigore matematico. L’immagine rovesciata, tracciata dalla luce, diventa legge ottica. E la camera oscura, strumento di meraviglia, entra nella scienza.

MYT-8- Della Porta, Kepler, and the camera obscura, ca. 1604. Johannes Kepler, imperial astronomer in Prague, published Ad Vitellionem Paralipomena in 1604, the foundation of modern optics. In it, he explains the geometric functioning of the camera obscura, linking it to human vision. His studies are based on the observations of Giovan Battista Della Porta, who had already described a camera obscura equipped with a lens in Magia Naturalis in 1589.

Kepler went beyond Della Porta’s empirical approach and formalized his insights with mathematical rigor. The inverted image traced by light became an optical law. And the camera obscura, an instrument of wonder, entered the realm of science.

MYT-9 – Huygens and Kircher. Netherlands–Rome, 1659–1671. Around 1659, Dutch physicist Christiaan Huygens created the first documented working magic lantern, as evidenced by his drawings and a letter to his brother.

Athanasius Kircher, a German Jesuit working in Rome, published the first printed illustration of a magic lantern in 1671, in the second edition of Ars Magna Lucis et Umbrae, inspired in part by demonstrations by the Danish engineer Walgensten, which he had seen in Rome.

MYT- 11 Prof. Charles. Paris, ca. 1789. During a public lecture in Paris around 1789, Jacques Charles demonstrated that it was possible to imprint the shadow of a human figure on paper soaked in silver chloride for a few minutes using a camera obscura. The image was unstable and disappeared shortly afterwards: there was still no method for fixing it.

The experiment was not described by him directly, but was remembered by witnesses and popularisers. Charles thus surprisingly anticipated the principle of chemical photosensitivity, which would later be exploited by Niépce and Daguerre.

Eliocromie pubblicate come cartoline, procedimento misto su base digitale: collage, incisione, ritocco a gouache e interventi manuali, e fa parte della prima serie I Misteri della Fotografia, dedicata ai miti ed ai precursori

Edizioni Atelier 41, via Fratelli Bandiera, Senigallia

La Fotografia è la più bella delle collezioni …

Senigallia, città della fotografia, ospitera nuovi spazi dedicato alla ricerca e promozione della fotografia.

Atelier 41 si trova 41 via fratelli Bandiera.

Senigallia diventerà la Città delle collezioni.

Any question : fotografia