Potassium fluosilicate, preparation

Gay Lussac and Thenard in 1809 obtained very impure amorphous silicon by passing silicon tetrafluoride over heated potassium. Berzelius in 1823 prepared elemental silicon in high purity by the same method. He also obtained silicon by heating potassium fluosilicate with potassium metal. Deville produced crystalline silicon in 1854 by electrolysis of a molten mixture of impure sodium aluminum chloride containing 10% silicon and a small quantity of aluminum. 

From the Latin words silex or silicis, meaning flint. Davy, in 1800, thought silica to be a compound and not an element later, in 1811, Gay Lussac and Thenard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride. In 1824, Berzelius, generally credited with the discovery, prepared amorphous silicon by the same general method and purified the product by removing the fluosilicates by repeated washings. Deville, in 1854, first prepared crystalline silicon, the second allotropic form of the element. 

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