The daguerreotype (
To make the image, a daguerrotypist would polish a sheet of
The image is on a mirror-like silver surface, normally kept under glass, and will appear either positive or
Several types of antique photographs, most often
The discovery and commercial availability of the halides:
Previous discoveries of photosensitive methods and substances—including
The first reliably documented attempt to capture the image formed in a
The images formed by means of a camera obscura have been found too faint to produce, in any moderate time, an effect upon the nitrate of silver. To copy these images was the first object of Mr. Wedgwood in his researches on the subject, and for this purpose he first used the nitrate of silver, which was mentioned to him by a friend, as a substance very sensible to the influence of light; but all his numerous experiments as to their primary end proved unsuccessful.
Daguerre met with Niépce and entered into correspondence with him. Niépce had invented an early internal combustion engine (the
The written contract drawn up between Nicéphore Niépce and Daguerre includes an undertaking by Niépce to release details of the process he had invented – the asphalt process or heliography. Daguerre was sworn to secrecy under penalty of damages and undertook to design a camera and improve the process. The improved process was eventually named the
Niépce's early experiments had derived from his interest in lithography and centered around capturing the image in a camera (then called a camera obscura) to result in an engraving that could be printed somehow by lithography. The asphalt process or heliography required exposures that were so long that Arago said it was not fit for use. Nevertheless, without Niépce's experiments, it is unlikely that Daguerre would have been able to build on them to adapt and improve what turned out to be the daguerreotype process.
After Niépce's death in 1833, his son, Isidore, inherited rights in the contract and a new version was drawn up between Daguerre and Isidore. Isidore signed the document admitting that the old process had been improved to the limits that were possible and that a new process that would bear Daguerre's name alone was sixty to eighty times as rapid as the old asphalt (bitumen) one his father had invented. This was the daguerreotype process that used iodized silvered plates and was developed with mercury fumes.
To exploit the invention four hundred shares would be on offer for a thousand francs each; secrecy would be lifted after a hundred shares had been sold, or the rights of the process could be bought for twenty thousand francs.
Daguerre wrote to Isidore Niepce on 2 January 1839 about his discussion with Arago:
He sees difficulty with this proceeding by subscription; it is almost certain – just as I myself have been convinced ever since looking on my first specimens – that subscription would not serve. Everyone says it is superb: but it will cost us the thousand francs before we learn it [the process] and be able to judge if it could remain secret. M. de Mandelot himself knows several persons who could subscribe but will not do so because they think it [the secret] would be revealed by itself, and now I have proof that many think in this way. I entirely agree with the idea of M. Arago, that is get the government to purchase this discovery, and that he himself would pursue this in the chambre. I have already seen several deputies who are of the same opinion and would give support; this way it seems to me to have the most chance of success; thus, my dear friend, I think it is the best option, and everything makes me think we will not regret it. For a start M. Arago will speak next Monday at the Académie des Sciences ...
Isidore did not contribute anything to the invention of the Daguerreotype and he was not let in on the details of the invention. Nevertheless, he benefited from the state pension awarded to him together with Daguerre.
Miles Berry, a patent agent acting on Daguerre's and Isidore Niépce's behalf in England, wrote a six-page memorial to the Board of the Treasury in an attempt to repeat the French arrangement in Great Britain, 'for the purpose of throwing it open in England for the benefit of the public.'
Inform party that Parliament has placed no funds
at the disposal of the Treasury
from which a purchase of this description could be made
The Treasury wrote to Miles Berry on 3 April to inform him of their decision:
(To) Miles Berry Esq 66 Chancery Lane
Having laid before the Lords &c your application on behalf of Messrs Daguerre & Niepce, that Government would purchase their Patent Right to the Invention known as the "Daguerreotype" I have it in command to acquaint you that Parliament has placed no Funds at the disposal of their Lordships from which a purchase of this description could be made
3rd April 1840 (signed) A. Gordon
Without bills being passed by Parliament, as had been arranged in France, Arago having presented a bill in the House of Deputies and Gay-Lussac in the Chamber of Peers, there was no possibility of repeating the French arrangement in England which is why the daguerreotype was given free to the world by the French government with the exception of England and Wales for which Richard Beard controlled the patent rights.
Daguerre patented his process in England, and Richard Beard patented his improvements to the process in Scotland During this time the astronomer and member of the House of Deputies
In the US,
Johnson's father travelled to England with some specimen portraits to patent the camera and met with Richard Beard who bought the patent for the camera, and a year later bought the patent for the daguerreotype outright. Johnson assisted Beard in setting up a portrait studio on the roof of the Regent Street Polytechnic and managed Beard's daguerreotype studio in Derby and then Manchester for some time before returning to the US.
Wolcott's Mirror Camera that gave postage stamp sized miniatures was in use for about two years before it was replaced by Petzval's Portrait lens that gave larger and sharper images.
His uncle, the banker Vital Roux, arranged that he should head the glass factory at Choisy-le-Roi together with
Early experiments required hours of exposure in the camera to produce visible results. Modern photo-historians consider the stories of Daguerre discovering mercury development by accident because of a bowl of mercury left in a cupboard, or, alternatively, a broken thermometer, to be spurious. 
Another story of a fortunate accident, which modern photo historians are now doubtful about, and was related by Louis Figuier, of a silver spoon lying on an iodized silver plate which left its design on the plate by light perfectly. Noticing this, Daguerre supposedly wrote to Niépce on 21 May 1831 suggesting the use of iodized silver plates as a means of obtaining light images in the camera.
Daguerre did not give a clear account of his method of discovery and allowed these legends to become current after the secrecy had been lifted.
Letters from Niépce to Daguerre dated 24 June and 8 November 1831, show that Niépce was unsuccessful in obtaining satisfactory results following Daguerre's suggestion, although he had produced a negative on an iodized silver plate in the camera. Niépce's letters to Daguerre dated 29 January and 3 March 1832 show that the use of iodized silver plates was due to Daguerre and not Niépce.