The next major technological innovation in neon lighting and signs was the development of fluorescent tube coatings. What may be the oldest surviving neon sign in the United States, still in use for its original purpose, is the sign “Theatre” (1929) at the Lake Worth Playhouse in Lake Worth Beach, Florida. The signs – dubbed "liquid fire" – were visible in daylight people would stop and stare. Neon lighting quickly became a popular fixture in outdoor advertising. Anthony purchased the two signs reading "Packard" for $1,250 apiece. In 1923, Georges Claude and his French company Claude Neon introduced neon gas signs to the United States by selling two to a Packard car dealership in Los Angeles. Over the next several years, patents were granted to Claude for two innovations still used today: a "bombardment" technique to remove impurities from the working gas of a sealed sign, and a design for the internal electrodes of the sign that prevented their degradation by sputtering. By 1913 a large sign for the vermouth Cinzano illuminated the night sky in Paris, and by 1919 the entrance to the Paris Opera was adorned with neon tube lighting. Claude's associate, Jacques Fonsèque, realized the possibilities for a business based on signage and advertising. This demonstration lit a peristyle of the Grand Palais (a large exhibition hall). From December 3–18, 1910, Claude demonstrated two 12-metre (39 ft) long bright red neon tubes at the Paris Motor Show. After 1902, Georges Claude's company in France, Air Liquide, began producing industrial quantities of neon, essentially as a byproduct of their air liquefaction business. Nutting and displaying the word "neon" may have been shown at the Louisiana Purchase Exposition of 1904, although this claim has been disputed in any event, the scarcity of neon would have precluded the development of a lighting product. Travers wrote, "the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget." Following neon's discovery, neon tubes were used as scientific instruments and novelties. Travers included the observation of a brilliant red glow in Geissler tubes. The discovery of neon in 1898 by British scientists William Ramsay and Morris W. Moore tubes were sold for commercial lighting for a number of years in the early 1900s. The direct predecessor of neon tube lighting was the Moore tube, which used nitrogen or carbon dioxide as the luminous gas and a patented mechanism for maintaining pressure. They were unsuitable for general lighting, as the pressure of the gas inside typically declined with use. Geissler tubes were popular in the late 19th century, and the different colors they emitted were characteristics of the gases within. When a voltage is applied to electrodes inserted through the glass, an electrical glow discharge results. The neon sign is an evolution of the earlier Geissler tube, which is a sealed glass tube containing a "rarefied" gas (the gas pressure in the tube is well below atmospheric pressure). Light emitting diode arrays can be formed to simulate the appearance of neon lamps. The signage industry has declined in the past several decades, and cities are now concerned with preserving and restoring their antique neon signs. In addition to signage, neon lighting is used frequently by artists and architects, and (in a modified form) in plasma display panels and televisions. The installations in Times Square, many originally designed by Douglas Leigh, were famed, and there were nearly 2,000 small shops producing neon signs by 1940. While they are used worldwide, neon signs were popular in the United States from about the 1920s to 1950s. They are the most common use for neon lighting, which was first demonstrated in a modern form in December 1910 by Georges Claude at the Paris Motor Show. In the signage industry, neon signs are electric signs lighted by long luminous gas-discharge tubes that contain rarefied neon or other gases. The large letters on the tower are illuminated in a timed sequence that repeats, "S", "ST", "STA", "STAT", "STATE", off. 1936 neon marquee sign for a theater in Auburn, California, as rebuilt in 2006.