Joseph Swan discovers in 1877 that heat can affect a photographic emulsion.

Swan, a British physicist and chemist, had begun working on a light bulb using carbonized paper filaments in an evacuated glass bulb in 1850 and in 1860 was able to demonstrate a working device.

However, the lack of a good vacuum and an adequate electric source had resulted in an inefficient bulb with a short lifetime.

Swan had returned to consider the problem of the light bulb in 1875 with the aid of a better vacuum and a carbonized thread as a filament.

The most significant feature of Swan's improved lamp is that there is little residual oxygen in the vacuum tube to ignite the filament, thus allowing the filament to glow almost white-hot without catching fire.

However, his filament has low resistance, thus needing heavy copper wires to supply it.

Swan will first publicly demonstrates his incandescent carbon lamp at a lecture for the Newcastle upon Tyne Chemical Society on December 18, 1878, but after burning with a bright light for some minutes in his laboratory, the lamp will break down due to excessive current.