What happens when silver iodide is heated?

1837, the French painter Daguerre exposed the silver iodide copper plate and heated it in a black box with mercury vapor. The silver iodide in the light-receiving part of the copper plate generates an image of the mercury-silver alloy, which is called "development".

Then rinse in hot salt water, and the silver iodide and sodium chloride that are not exposed to light lose their photosensitivity and dissolve in water.

The image composed of mercury and silver alloy is permanently fixed on the copper plate, thus completing the "fixing".

The "silver plate method" has high photographic sensitivity and fine particles, and the exposure time is only 20-30 minutes.

The invention of "silver plate method" photography marks the birth of photography.

Paris Temple Street 1838. Daguerre/photo.

This is the first photo of a city street in the world, and it is also the first photo of a person taken by the "silver plate" photography method (there is a person shining shoes in the lower left corner).

1839, 19 In August, at the joint meeting of the French Academy of Sciences and the French Academy of Arts, Aragon, director of the National Astronomical Observatory in Paris, France, made a photographic report, announcing the birth of photography on the "silver plate" photography invented by Daguerre.

1844, Yule eger wears a portrait photo taken by China officials with the "silver plate method".

1844 10 a French photographer, Yule Egel, as the chief prosecutor of French customs, accompanied the French diplomatic mission and came to Macau with Daguerre's "silver plate method" camera.

I took the earliest photos of Macau and became the earliest photos of China. Macau became the first place in China to record video materials.

1844 10, Macau, a glimpse of the South Bay scenery.

Later, he arrived at Huangpu Port in Guangzhou and took a batch of the earliest photos of Chinese mainland, including the bust of the Governor of Guangdong and Guangxi-the portrait of the elderly.