Note 4 bis — Chapter XVIII · SILICON AND THE OTHER ELEMENTS OF THE FOURTH GROUP

It is very remarkable that silicon decomposes carbonic anhydride at a white heat, forming a white mass which, after being treated with potassium hydroxide and hydrofluoric acid, leaves a very stable yellow substance of the formula SiCO, which is formed according to the equation, 3Si + 2CO2 = SiO2 + 2SiCO. It is also slowly formed when silicon is heated with carbonic oxide. It is not oxidised when heated in oxygen. A mixture of silicon and carbon when heated in nitrogen gives the compound Si2C2N, which is also very stable. On this basis Schützenberger recognises a group, C2Si2, as capable of combining with O2 and N, like C.

We may add that Troost and Hautefeuille, by heating amorphous silicon in the vapour of SiCl₄, obtained crystalline silicon, and probably at the same time lower compounds of Si and Cl were temporarily formed. In the vapour of TiCl₄ under the same conditions crystalline titanium is formed (Levy, 1892).