The invention of photography is variously said to have taken place in 1824 (Nicéphore Niépce’s Heliography); 1829 (Daguerre discovered the light – sensitivity of iodized silvered plates); or 1839 when Daguerre announced his invention, the Daguerreotype, to the world – the same year Fox Talbot made public his paper process, the Calotype). Yet, investigations which, in one form or another, contributed to the work of Niépce, Daguerre, and Fox Talbot date back as far as the time of Aristotle, if we consider the significance of the principle that objects themselves emit the light rays which meet the eye. But it is the work of three eighteenth- century scientists that most directly contributed to the invention of photography as we know it: Johann Heinrich Schulze (1687 – 1744), Giacomo Battista Beccaria (Beccarius) (1716 – 1781), and Carl Wilhelm Scheele (1742 – 1786).
Early “Inventors” of Photography
Johann Heinrich Schulze was appointed professor of medicine in 1720, and of Greek and Arabic in 1729, at the University of Altdorf; he was later called to the University of Halle as professor of medicine, rhetoric and archaeology. Outside of his numerous academic pursuits, Schulze conducted many chemical experiments, attempting to reproduce the luminous stone of Balduin. While still in Altdorf, he once saturated chalk with nitric acid which happened to contain a small amount of silver performing his experiment near an open window, he observed that the portion of the precipitate that faced the window had fumed purple, whereas that part not facing the window remained in its original state (white).
Schulze was so taken by this unexpected development that he put aside his original experiment and began to investigate the cause of the unusual change he had observed. His first test, using fire to heat the precipitate, proved that the change was not due to heat. He then divided the mixture into two parts, leaving one in the dark and exposing the other to the sunlight. On the bottle exposed to sunlight, Schulze placed a small piece of string around it. After several hours in direct sunlight, Schulze removed the string and found that the precipitate under the string had remained the same color as the precipitate that had not been exposed to any sunlight. Schulze then put the portion of the precipitate that had been kept in the dark into the bottle, and placed a sheet of paper, from which letters and words had been cut out, onto it.
Before long I found that the sun’s rays on the side on which they had touched the glass through the apertures in the paper, wrote the words or sentences so accurately and distinctly on the chalk sediment, that many people curious in such matters but ignorant of the nature of the experiment, were led to attribute the result to all kinds of artifices.
Having forgotten that there had been a small amount of silver in the original mixture, Schulze made a new mixture of nitric acid and salt and repeated the experiment. Puzzled by his lack of success, it was some time before he remembered that he had had some silver in the original experiment. Schulze then mixed up a solution with a stronger silver mixture and observed that the discoloration took place more rapidly. He noticed that the sediment was further darkened by the addition of more silver. Schulze related the details of his discovery to the Imperial Academy in Nurnberg under the title “Scotophorus pro Phosphoto Inventus”. It was a sort of paradox that the sun should produce darkness, points out Gernsheim. Schulze had been searching for `phosphorous’, bringer of light, and discovered `Scotophorous’, bringer of darkness.
Schulze related the considerable importance that he attached to his experiments in his posthumously-published “Chemische Versuche”. He stresses the significance of the discovery of the light-sensitivity of carbonate of silver and, even more significantly, the independence of the sunlight’s chemical effects from those of heat.
Unfortunately, Schulze did not seek any practical applications for his discovery (Gernsheim, 20). He did not spread the nitrate of silver onto paper, for example, and attempt to produce images by the same process through which he achieved the fixing of letters and sentences onto the solution through a bottle. Thus, his experiments remained by-and-large unnoticed until Eder called attention to them in his `Geschichte der Photographie’ in 1881, in which he names Schulze as the `inventor of photography’. As Gernsheim points out in `The Origins of Photography’, Eder is, technically speaking, correct if we translate `photography’ literally as `light-writing, because Schulze had written words and sentences in the solution in the bottle. However, he adds, the term `photography’ was first used in 1839 to denote the “making of permanent pictures” through the action of light. From Schulze does, however, “stem the whole genealogical tree of photochemistry, which, combined with the camera obscura, eventually produced photography.”
But it was the investigations of the Italian physicist Beccaria, based on the work of Reaumur and Duhamel, that led him to discover the sensitivity of silver chloride to light. Beccaria, who wrote in Latin and signed his name ÄBeccariousÄ, was a membre of a religious order, taught rhetoric and philosophy in Rome and Palermo and physics at the University of Turin and was interested almost exclusively in the study of artificial and atmospheric electricity.
Beccariouis took freshly precipitated hornsilver, placed it in a bottle and observed that the side facing the light turned blue whereas the opposite side remained whitish. When the whitish side was turned to face the light, it, too, turned blue. This, states Eder, conviced him that it was the effect of the light, not the air as he had previously believed, that caused the change of color.
Eder points out that Beccarious could not have known of the work of Schulze because in his essay of 1757, he does not make mention of his work. The procedures which Beccarious used were similar in nature to those of Schulze; though Schulze employed `kreidehaltigen Sivermagna’, Beccarious experimented with silver chloride. Beccarious states that there is a certain “force” in light that could change colors of certain objects. He concluded that it is not air, but light that darkens silver chloride and adds that one must have a thorough knowledge of the three causes, light, air and heat, in order to study the change of colors.
Carl Wilhelm Scheele, a renowned swedish chemist who is responsible for many important discoveries in chemistry, also recognized the reaction of silver chloride to light. Scheele was familiar with Schulze’s investigations and based his own work, Aeris atque ignis examen chemicum, which is of particular significance to the history of photography, on the posthumously-published work by Schulze. Many writers, such as Landgrebe (Über das Licht, 1834), Becquerel (La Lumière, 1868), Hardwich (A Manual of Photographic Chemistry, 1863) and Muspratt (Enzyklopädisches Handbuch der technischen Chemie, 1878), list him as the founder of photochemistry. Eder states that “…he is undoubtedly entitled to recognition for his services in carrying out his experiments in a more systematic and clear-sighted manner than his predecessors.”
Scheele originated the chemical conception of the reaction of silver chloride to light and the photohistory of the solar spectrum. He used silver chloride paper in his experiments and was familiar with the different reactions of silver chloride. Not only did he observe the difference in behavior of silver chloride blackened by light, but he also wrote of the insolubility of silver chloride in ammonia. This observation was overlooked in the beginning of the nineteenth century by both Wedgwood and Davy, for whom an understanding of its significance, as Gernsheim wrote, might have provided a way to produce a partially-acceptable fixing agent. Gernsheim justifiably feels that photography might have been developed around 1800 had this information been put to use.
Another significant experiment by Scheele is one to which he attached little importance. Powdered silver chloride, exposed to the full spectrum of sunlight, was blackened more easily by the violet of the spectrum than by other rays, showing that violet rays are more chemically active than other rays. (Note: The more pronounced darkening effect of the violet rays proved to be a source of great consternation to early photographers, who were frustrated by the manner in which subjects, affected by these rays, were rendered onto sensitized black-and-white material.) This important discovery came in the course of an experiment in which Scheele was attempting to prove that light itself cannot be considered to be a simple substance or element.
Scheele concluded incorrectly that light was decomposed by the silver chloride by placing silver chloride into a glass throught which no light might enter, and exposing it to constant sunlight for a long period of time. The silver chloride did not blacken, although the glass itself became quite hot. Scheele eliminated consideration of the possibility, as did Schulze, that the blackening might be caused by heat, but stated that the light is probably not pure `phlogiston’ but combines along with heat and the `silver chalk’ to effect a blackening. In the English translation of Scheele’s work by J.R. Forster, F.R.S., Richard Kirwin, who added some explanatory notes, stated that he doubts that the light consisted of `phlogiston and fire’ and reasoned that `combustible matter ordinarily does not penetrate solid matter as does light; that, on the other hand, light does not generally reduce metal oxides of manganese dioxide’. Kirwan seemed to believe that the light sprang from a strong motion of the elementary fire, whereby the combustible matter was expelled from the objects which were exposed to light.
Therefore, we can credit the work of Schulze, Baccarious and Scheele as representing the first useful developments which, during the first four decades of the nineteenth century, culminated in the “perfection” of what became known as “photography” and which, despite vast improvements to, and countless changes in the manner in which the early scientists’ findings are not being utilized, still forms the very basis of modern-day technology.
Eder, Joseph Maria. Johann Heinrich Schulze. Wien: K.K. Graphische Lehr- und Versuchsanstalt, 1917.
— Geschichte der Photographie. Wien, 1932.
Dr. Joh. Heinr. Schulzes Chemische Versuche, nach dem eigenhändigen Manuscript des Herrn Verfassers zum Druck befordert durch D. Christoph Carl Strumpff. Halle, 1745
Hardwich, T. Frederick. A Manual of Photographic Chemistry. London, 1864.
Potonniee, Georges. The History of the Discovery of Photography. New York, 1936.
Sipley, Louis Walton. Photography’s Great Inventors. Philadelphia, 1965.
Schulze, Heinnch Johann. Scotophorus (Dunkelheitsträger) anstatt Phosphorus (Lichtträger) entdeckt, oder merkwürdiger Versuch über die Wirkung der Sonnenstrahlen. Nürnberg, 1727.
Scheele, Carl Wilhelm. Chemische Abhandlung von der Luft und dem Feuer. Uppsala and Leipzig, 1777.
Jonathan B. Spira is the CEO and Chief Analyst at Basex. This article was originally published in The Photographist.