Photographic fixing with thiosulfate (Herschel)
Fijado fotográfico con tiosulfato (Herschel)
- Date
- 1819-1839 · confidence high
- Place
- Slough, England, United Kingdom
- Credited to
- John Herschel
- Field
- Matter & energy
What was discovered
Herschel discovers in 1819 that sodium hyposulfite (thiosulfate) dissolves silver salts, and in 1839 suggests using it to fix photographic images. It made the daguerreotype and the calotype permanent.
Daguerre fixed with common salt and Talbot at first with salt and iodide; thiosulfate prevailed for its effectiveness.
What it led to
- permanent photographic images
- Herschel's terms photography, negative and positive
- 19th-century processes that led to roll film