Nitride of silicon is a bluish, fibrous-looking body, formed when silicon is heated in nitrogen gas.
Sulphide of silicon burns in sulphur vapour, gene. rating bieulphide. The same body may be formed on passing bisulphide of carbon over a heated mixture of carbon and silica. It is -a white, earthy-looking powder.
Beostide of silicon may be obtained, but iodide does not seem to exist.
Silicon and ciclorise form two oompounds corresponding to the two oxides.
I. Itydrochlorate of protochloride of silicon (2HCI,3SiCI).—Tlic method of preparing this body has already been described in con nection with protoxide of silicon. It is a colourless liquid, refracting light powerfully ; emits suffocating fumes on exposure to air; is inflammable, burning with a pale green flatuo; and is decomposed at a red heat.
2. Chloride of silicon or rather, Lichloride of silicon.— Finely powdered silica Is made into a dough.liko mans with lamp black and oil, and heated to redness in a covered crucible ; a porcelain tube filled with fragments of the resulting masa is strongly ignited end a current of dry chlorine passed through it ; the following decom position occurs :— SiO, + CI, -1- C, = 21C0) file', Silica. Chlorine. Carbon. Carbonic Ilichtorido of
oxide, silicon.
The chloride of silicon vapour must be condensed by the aid of a freezing mixture, for it is very volatilo. It is a transparent, colourless liquid ; fumes in the air, and has an irritating odour.
ChloroaulAidcs of silicon and may be formed by the reaction of chloride of silicon vapour and dry hydro sulphuric acid gas at a red heat.
Fluoride of silicon (SiF,) or fluosilicic acid, and ailicofluoric or hydrofluosilicie acid (HF,SiF,) have been described under FLUORINE.
Detection of silicon.—The presence of this element in such a substance as glass, or any transparent mineral, is readily demonstrated by the etching action of hydrofluoric acid. From solution it is precipitated as gelatinous silica on the addition of hydrochloric acid. Silica may also be individualised from its property of being after ignition insoluble in all acids, except hydrofluoric, but soluble iu fused caustic alkali.
Eltimation of ailicon.—This is always performed in the state of recently dried and anhydrous silica, which contains per cent of silicon, and of oxygen.