page_title: Science and technology of the Tang dynasty
section_title: Alchemy, gas cylinders, and air conditioning
hierarchical_section_title: Science and technology of the Tang dynasty / Alchemy, gas cylinders, and air conditioning
caption_attribution_description: English: Plate offering, North China, 8th century, glazed terracotta "three colors" on engobe, incised decoration. Musée Guimet, Paris. MA 4021 Français&#160;: Plat à offrandes, Chine du Nord, 8ème siècle, terre cuite à glaçure "trois couleurs" sur engobe, décor incisé. Musée Guimet, Paris. MA 4021
context_page_description: The Tang dynasty of ancient China witnessed many advancements in Chinese science and technology, with various developments in woodblock printing, timekeeping, mechanical engineering, medicine, and structural engineering.
context_section_description: The Chinese of the Tang period employed complex chemical formulas for an array of different purposes, often found through experiments of alchemy. These included a waterproof and dust-repelling cream or varnish for clothes and weapons, fireproof cement for glass and porcelain wares, a waterproof cream applied to silk clothes of underwater divers, a cream designated for polishing bronze mirrors, and many other useful formulas. The vitrified, translucent ceramic known as porcelain was invented in China during the Tang, although many types of glazed ceramics preceded it.
  Ever since the Han dynasty (202 BC - 220 AD), the Chinese had drilled deep boreholes to transport natural gas from bamboo pipelines to stoves where cast iron evaporation pans boiled brine to extract salt. During the Tang dynasty, a gazetteer of Sichuan province stated that at one of these 182 m (600 ft) 'fire wells', men collected natural gas into portable bamboo tubes which could be carried around for dozens of km (mi) and still produce a flame. These were essentially the first gas cylinders; Robert Temple assumes some sort of tap was used for this device.
  The inventor Ding Huan (fl. 180 AD) of the Han dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (10 ft) in diameter and manually powered. In 747, Emperor Xuanzong had a "Cool Hall" built in the imperial palace, which the Tang Yulin (唐語林) describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains. During the subsequent Song dynasty, written sources mentioned the air conditioning rotary fan as even more widely used.
caption: A rounded ceramic plate with "three colors" (sancai) glaze design, 8th century
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