Georges Claude

Georges Claude
Georges Claude in 1926
Born	24 September 1870 Paris, France
Died	23 May 1960 (aged 89) Saint-Cloud, France
Fields	Engineering
Known for	Claude cycle Neon lighting Ocean energy conversion
Notable awards	Leconte Prize (1921)

Georges Claude (24 September 1870 – 23 May 1960) was a French engineer and inventor. He is noted for his early work on the industrial liquefaction of air, for the invention and commercialization of neon lighting, and for a large experiment on generating energy by pumping cold seawater up from the depths. He has been considered by some to be "the Edison of France". Claude was an active collaborator with the German occupiers of France during the Second World War, for which he was imprisoned in 1945 and stripped of his honors.

Georges Claude studied at the École supérieure de physique et de chimie industrielles de la ville de Paris (ESPCI). He then held several positions. He was an electrical inspector in a cable factory and the laboratory manager in an electric works. He founded and edited a magazine, L'Étincelle Électrique (The Electric Spark); his important friendship with Jacques-Arsène d'Arsonval apparently dates from this time. About 1896, Claude learned of the explosion risk for bottled acetylene, which was used at the time for lighting. Acetylene is explosive when stored under pressure. Claude showed that acetylene dissolved well in acetone, equivalent to storing it under 25 atmospheres of pressure, reduced the risk in handling the gas.

In 1902 Claude devised what is now known as the Claude system for liquifying air. The system enabled the production of industrial quantities of liquid nitrogen, oxygen, and argon; Claude's approach competed successfully with the earlier system of Carl von Linde (1895). Claude and businessman Paul Delorme founded L'Air Liquide, S.A. (Air Liquide), which is presently a large multinational corporation headquartered in Paris, France.

Inspired by Geissler tubes and by Daniel McFarlan Moore's invention of a nitrogen-based light (the "Moore tube"), Claude developed neon tube lighting to exploit the neon that was produced as a byproduct of his air liquefaction business. These were all "glow discharge" tubes that generate light when an electric current is passed through the rarefied gas within the tube. Claude's first public demonstration of a large neon light was at the Paris Motor Show (Salon de l'Automobile et du Cycle), 3–18 December 1910. Claude's first patent filing for his technologies in France was on 7 March 1910. Claude himself wrote in 1913 that, in addition to a source of neon gas, there were two principal inventions that made neon lighting practicable. First were his methods for purifying the neon (or other inert gases such as argon). Claude developed techniques for purifying the inert gases within a completely sealed glass tube, which distinguished neon tube lighting from the Moore tubes; the latter had a device for replenishing the nitrogen or carbon dioxide gases within the tube. The second invention was ultimately crucial for the development of the Claude lighting business; it was a design for minimizing the degradation (by "sputtering") of the electrodes that transfer electric current from the external power supply to the glowing gases within the sign.