1194 ZOSTERA 



employ zirconin, instead of lime or magnesia, in the preparation of cylinders for the 

 oxyhydrogen light. 



ZIRCONIUM may be prepared in an amorphous form by passing the vapour of 

 chloride of zirconium over heated sodium, or by heating the double fluoride of zirconium 

 and potassium with an alkaline metal, and treating the product with dilute nitric acid. 

 Thus prepared, it appears as a dull brown powder, combustible in the air at a tem- 

 perature below redness. 



M. Troost wished to determine whether zirconium, already found in this amorphous 

 state by Berzelius, was a metal similar to magnesium, or aluminium, or a metalloid 

 not unlike carbon, boron, or silicon. He obtained crystallised zirconium by heating 

 the fluoride of zirconium and potassium with excess of aluminium, and removing the 

 aluminium by solution from the insoluble residue. The zirconium thus obtained 

 appears in hard brittle crystalline laminae, of specific gravity 4'15. 



Zirconium in its chemical properties approaches near to silicium, and perhaps even 

 nearer to titanium. Crystalline zirconium withstands the action of oxygen at a red 

 heat, becomes slightly oxidised at a white heat, and burns only when subjected to the 

 oxyhydrogen-flame. It burns in chlorine, however, at a dull heat. Cold acids have 

 no action upon it, and warm acids affect it but slightly. Its true solvent is hydro- 

 fluoric acid. Like silicium, zirconium presents three different physical conditions, viz. 

 the amorphous, graphitoi'd, and crystallised. Zirconium forms only one oxide, known 

 as zirconia. 



ZIZAITXA.. It has recently been suggested to employ Canada Grass (Zizania 

 aquatica) as a paper-making material. This plant grows abundantly on the shores 

 of Lakes Erie, Ontario, and St. Clare, and is known to the Indians as Tttscarora. The 

 fibre is said to be easily bleached and comparatively free from silica, while it yields 

 a paper of good colour and texture, well adapted to the printer's use. It is asserted 

 that a supply of 100,000 tons per annum may be readily obtained from Canada. 



ZIZYPHITS. Several species of this genus of the Buckthorn order (Rhamnacea) 

 yield edible fruits. Z. Jujuba, and some others, furnish the fruit known as jujube. 



ZOR6XTE. A selenide of lead and copper, from Zorge and Tilkerode in the 

 Hartz, 



ZOSTERA. The Grass-wrack (Zostera marina) is a marine plant common on 

 the coast of Britain. It is collected and dried for use as a substitute for hay in 

 packing. 



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