Why Kodak Film Sensitivity Depended on Cows and Mustard

The working dose Samuel Sheppard wrote into his patent was 2 to 3 grains of thiosinamine per 100 pounds of dry gelatin, which works out to roughly three or four parts per million. Added to a gelatin stripped of its natural sensitizer, that trace could raise the emulsion's sensitivity by a factor of ten or twenty. Nudge it upward and the film fogged.

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