ZIRCONIUM. 52? 



deity Thor. The metal was obtained from the chloride, and 

 exhibited a general resemblance to aluminum. Like yttrium, 

 it burns in oxygen with a degree of brilliancy which is quite 

 extraordinary $ the resulting oxide does not exhibit the slightest 

 trace effusion. 



Thorina is considered a protoxide, Th O. Its density is 

 9.402, and therefore superior to that of all other earths. It re- 

 sembles yttria in being insoluble in alkalies, but differs from 

 that earth in the peculiar property of its sulphate, to be preci- 

 pitated by ebullition, and to redissolve entirely, although in a 

 slow manner, in cold water. Its sulphate also forms a double 

 salt with sulphate of potash, which dissolves in water, but is 

 insoluble in a liquor saturated with sulphate of potash. 



ZIRCONIUM. 

 Eq. 420.2 or 33.67 ; Zr. 



Zirconium is obtained by heating the double fluoride of zir- 

 conium and potassium, with potassium, in a glass or iron tube. 

 On throwing the cooled mass into water, the zirconium remains 

 in the form of a black powder, very like that of charcoal. It 

 contains an admixture of hydrate of zirconia, which may be 

 withdrawn from it by digestion in hydrochloric acid, at 104 

 (40 cent.) The zirconium is afterwards washed with sal am- 

 moniac to remove completely chloride of zirconium, and then 

 with alcohol to withdraw the sal ammoniac. If washed with 

 pure water, it is apt to pass through the filter. After being thus 

 treated, the powder assumes, under the burnisher, the lustre of 

 iron, and is compressed into scales which resemble graphite. 

 When heated in air it takes fire below redness. It is very 

 slightly attacked by either alkalies or acids, with the exception 

 of hydrofluoric acid, which dissolves it with evolution of hydro- 

 gen. 



The constitution of zirconia is not certainly known, but it is 

 believed to be analogous to that of alumina, Zr 2 O 3 . It was 

 first recognised as a peculiar earth by Klaproth in 1 78!), who 

 discovered it in the zircon of Ceylon, a silicate of zirconia, which 

 is also found in the syenitic mountains of the south-east side of 

 Norway. The hyacinth is the same mineral of a red colour ; 



M M 



