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inventor of the incandescent-filament electric lamp and of bromide paper
for use in developing photographs. Swan took out more than 70 patents. He made a miner's electric safety lamp which was the ancestor of the modern miner's lamp. In the course of this invention he devised a new lead cell (battery) which would not spill acid. He also attempted to make an early type of fuel cell. Swan was born in Sunderland and went to work in a chemical firm. Interested in electric lighting from about 1845, he began making filaments by cutting strips of paper and baking them at high temperatures to produce a carbon fibre. In making the first lamps, he connected the ends of a filament to wire (itself a difficult task), placed the filament in a glass bottle, and attempted to evacuate the air and seal the bottle with a cork. Usually the filament burned away very quickly in the remaining air, blackening the glass at the same time. Only after the invention of the vacuum pump 1865 was Swan able to produce a fairly durable incandescent lamp. For this he made a new type of filament from cotton thread partly dissolved by sulphuric acid. He patented the process in 1880 and began manufacturing lamps. In 1882 US inventor Thomas Edison initiated litigation for patent infringement against Swan, but this was dismissed and the joint company Edison and Swan United Electric Light Company came into being in 1883. A wet process for producing photographic prints, using a gelatine film impregnated with carbon or other pigment granules and photosensitized using potassium dichromate, was patented by Swan in 1864. This was known as the carbon or autotype process. |