1 gen 1777 anni - Carl Wilhelm Scheele (Sweden): light darkened silver chloride by disintegrating it into microscopic dark particles of metallic silver.

Descrizione:

Of greater potential usefulness, Scheele found that ammonia dissolved the silver chloride, but not the dark particles. This discovery could have been used to stabilize or "fix" a camera image captured with silver chloride, but was not picked up by the earliest photography experimenters.

Scheele also noted that red light did not have much effect on silver chloride, a phenomenon that would later be applied in photographic darkrooms as a method of seeing black-and-white prints without harming their development.

Although Thomas Wedgwood felt inspired by Scheele's writings in general, he must have missed or forgotten these experiments; he found no method to fix the photogram and shadow images he managed to capture around 1800.

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