ZIRCONIUM (Zr). A rare metal found in the minerals zircon and hyacinth, which contain the oxide of the metal united with silicic acid. To obtain the metal, the double fluoride of potassium and zirconium is to be strongly heated with potassium; from the cold residue diluted hydrochloric acid dissolves out everything except pulvcrulent zir conium, which must be washed first with solution of chloride of ammonium and then with alcohol. Zirconium has not yet been fused: obtained in the manner just described It presents the appearance of a black powder, which assumes a slight metallic lustre under the burnisher and scarcely conducts an electric current. Zirconium in this pulverulent form Indicates the properties of the massive metal as little as pulverulent aluminium did those of the latter beautiful metal before it was obtained in malleable masses by Bunsen and Devine. When heated below redness in air or oxygen, zirconium takes fire and burns with a very intense light, producing zirconia. It is also gradually oxidised in boiling water, diluted hydrochloric and sulphuric acids do not act upon it, but hydrofluoric acid dissolves it with evolution of hydrogen. Tho equivalent of zirconium is 33.0 if zirconia be written but If written ZrO, the equivalent is 22.4.
Zireonia or Zr0,). Zirconium and oxygen form only one compound, zirconia, which is obtained by fusing finely-powdered zircon with caustic potash or soda and then dissolving the fused mass in dilute hydrochloric acid. Excess of acid and moisture are expelled by beat, when on the addition of water the chlorides of zirconium and potassium or sodium are dissolved, leaving insoluble silica ; from this solution excess of ammonia precipitates zirconia as hydrate, which must be washed, dried, and ignited. It then presents the appearance of a white infusible and insoluble powder. The hydrate is gelatinous, insoluble in the caustic alkalies, but readily soluble in acids, and sparingly so in carbonate of ammonia.
Zirconla forma salts with acids, which possess the following characters:—They have an astringent taste ; they are precipitated by the caustic alkalies potash and soda, and an excess of them does not redissolve the precipitate. When boiled with sulphate of potash, a subsalt of zirconia is formed, and being insoluble subsides. Infusion of galls produces a yellow precipitate, and phosphate of soda a white one : carbonate of zireonia, when recently precipitated, is soluble in bicarbonate of ammonia and of potash.