ZIRCONIUM, a chemical element named after the mineral zircon in which Klaproth dies covered the oxide zirconia (1789), and obtained by Berzelius in 1824 as an iron-gray powder. Afterward found in many other minerals. some of the most important being eudialyte, hyacinth, polymignite, etc. It has many physical and chemical properties resembling the element sal con. Like silicon and carbon it exists free la three allotropic forms: the amorphous. obtained as a black powder by heating sodium zirconium chloride with metallic sodium or potassium; the cryctalline, as foliated leaves from heats so- dium zirconium fluoride with metallic num; and the graphitoidal, obtained in scales of a steel gray color by action of iron on solfanm zirconium. Symbol Zr; atomic weight %U. specific gravity 4.15. The element is ooh- sloth* soliible in hydrochloric or sulphuric acids. but is readily so in aqua regia or hydrofluoric aciii When heated highly in the air it burns to the oxide ZrOs. This oxide, commonly known as zirconia, is prepared by fusing the mineral zircon (ZrSi0.) with a mixture of sodium hydrate and sodium carbonate, treating with hydrochlo ric acid and heating to separate the silica, pre cipitating the solution so obtained with ammo nia, and heating this white precipitate. An other method is now used by which the chloride is made by treating crushed zircon with chlo rine, separating the silicon by heat, pre cipitating the solution of zirconium chloride with ammonia, and heating the precipitate. Zir
conia forms a white powder or amorphous lumps. It has both basic and acid properties. It dissolves slowly in hydrofluoric or sulphuric acids, the fluoride (ZrF.) uniting with fluorides of other metals forming complex salts called zircofluorides, example K2rF., potassium zirco fluoride. With strong alkalies zirconia forms :neonates, example, K2r0., potassium zirco nate. Zirconium forms a long series of salts, in most of which it acts as a basic element.
Zirconia possesses the power of be ing extremely refractory toward heat, not being changed even by that of the oxy-hydrogen blow pipe flame. It also has great radiating power. Because of this it is used in the "zirconta light,* a light used considerably in lighthouses. A cone of zirconia is played upon by the very hot flame of the oxy-hydrogen blowpipe so that it glows with a very intense white light. While this is the principal use of compounds of zir conium, certain minerals containing it are found as clear beautiful statics and are used as gems.