Updated 06-I-2018

Rudolf Langhans
This article is based on a document of fellow lamp engineer and collector Edward J. Covington, which appeared on his website of biographical sketches of persons involved in the lamp industry. Following his passing in February 2017 and with kind permission of his family, Ed's words have been preserved and subsequently expanded with new material by this author, to maintain continued access to the research he initiated.


Biography
In the latter part of the 1880s and the early part of the 1890s Rudolf Langhans, of Berlin, Germany, did experimental work on a new filament that involved silicon. Such a lamp is in the William J. Hammer Collection7. The lamp was brought out in England in 1899 under the name of 'Premier filament'. Quoting from an article in Electrical World and Electrical Engineer3:
"The filament consists of carbide of silicon coated with silicon and carbon and is said to be capable of standing a higher temperature than pure carbon..."
From 1891 to 1893 Langhans worked at the Lynn plant of the Thomson-Houston Company on a cellulose filament impregnated with silicon but a successful product did not result before the factory closed operations in August, 1893. He worked under the direct supervision of Elihu Thomson and John E. Randall6.


References & Bibliography
  1. "Filament for Incandescent Lights", Rudolf Langhans, U.S. Patent 420,881, dated Feb 4 1890. Application filed Apr 5 1888. Patented in Germany Nov 9 1887; in France Feb 15 1888; in England Feb 18 1888; in Belgium Feb 20 1888; in Italy Feb 21 1888.
  2. "The Langhans Incandescent Lamp", The Electrical Engineer, Vol.9, Apr 23 1890, p.277.
  3. "Filament of Carbide of Silicon", Electrical World and Electrical Engineer, Vol.XXXIII No.13, Apr 1 1899, p.415.
  4. "Process of Manufacturing Incandescent Bodies", Rudolf Langhans, U.S. Patent 660,114, dated Oct 23 1900.
  5. "Incandescent Lamp", Rudolf Langhans, U.S. Patent 516,892, dated Mar 20 1894.
  6. Letter to F. W. Willcox from H. D. Burnett, titled "Notes on Development of the Carbon Incandescent Lamp at the Lynn Lamp Works of the Thomson-Houston Electric Company", Apr 12 1911.
  7. "The William J. Hammer Historical Collection of Incandescent Electric Lamps", William J. Hammer, Transactions of the New York Electrical Society, 1913, No.4, p.15.