A Question From Antiquity Is Answered

Neutron absorption Thermal neutron capture cross section 0.167 barns 

During the centuries of antiquity and the Middle Ages, the technology of glassmaking was developed to a high level, regarding both craftsmanship and artistry. 

The question about the central substance in glass and quartz remained unanswered however. And nor did the 18 century, with its great development within chemistry, see the solution of the problem. Torbem Bergman in Uppsala designated quartz as an earth, thus as an oxide, very difficult to reduce. 

In the early W century Humphry Davy attacked the problem. He was convinced that quartz was not an element. Was it instead the oxide of an unknown metal He utilized powerful methods in order to reveal the content of the white siliceous stone. He dissolved silicic acid in alkali and electrolyzed it with the voltaic pile. He let potassium vapor pass over quartz at high temperature. No substance with metallic temperament appeared. J.-L. Guy-Lussac and L. J. Thenard in Paris tried another way. They made silicon tetrafluoride 

SiF by letting gaseous hydrofluoric acid HF pass over quartz. The tetraflu-oride formed was allowed to pass over hot potassium metal. In a violent reaction a reddish-brown powder was formed. Perhaps an impure elementary silicon. 

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