SWAN, SIR JOSEPH WILSON English physicist and electrician, was born at Sunderland on Oct. 31, 1828. After serving his apprenticeship with a druggist in his native town, he became first assistant and later partner in a firm of manufacturing chemists in Newcastle. Among its opera tions this firm included the manufacture of photographic plates, and thus Swan was led to one of the advances in photography with which his name is associated—the production of dry plates, which were the outcome of an original observation made by him on the effect of heat in increasing the sensitiveness of a gelatine bromide of silver emulsion. In 1862 he patented the first com mercially practicable process for carbon printing in photography (See PHOTOGRAPHY.) In 1879 Swan patented bromide paper.
In 186o, he produced an electric lamp with a carbon fila ment, which was formed by packing pieces of paper or card with charcoal powder in a crucible and subjecting the whole to a high temperature. The carbonized paper thus obtained he mounted in the form of a fine strip in an evacuated glass vessel and con nected it with a battery of Grove's cells, which though not strong enough to raise it to complete incandescence, were sufficient to make it red-hot. This was substantially the method adopted by
Edison nearly twenty years later.
Subsequently Swan devised a cotton thread "parchmentized" by the action of sulphuric acid, and on the loth of October 188o he gave at Newcastle the first public exhibition on a large scale of electric lighting by means of glow lamps. In another method devised by him, collodion was squirted into a coagulating solution and the tough threads thus obtained carbonized by heat. He also devoted attention to apparatus for measuring electric currents, to the improvement of accumulators and to the conditions govern ing the electro-disposition of metals. Swan was knighted in Holding many honours, he died at Warlingham on May 27, 1914.