1839.] 



On Chemical Tests. 



the blow-pipe a fine green glass, which appears brown when hot, and 

 when tin is added the colour becomes blue. 



127. VITKIA. Pure hydrate of yttria has a white colour which 

 ignition turns dirty yellow. It easily t dissolves in acids, forming salts 

 having a sweet astringent taste. The following tests indicate yttria. 



J^monia \ Wnite voluminous precipitate insoluble in excess, 

 ZlZt$ P — ia }»<>• soluble in excess. 



oS a ^ fSBda } Do - ".uble in muriatic acid. 

 Hydrosulphuret ammonia, a precipitate of yttria. 



Liquid sulphuretted hydrogen ) Nq precipUate . 

 sulphuretted hydrogen gas. j 



Prussiate potass, white chalky precipitate. 



«. The solutions of the neutral salts of yttria redden litmus paper* 



b. Solutions of yttria are distinguished from solutions of alkalieSj 

 barytes, strontian, lime, and magnesia, in the same manner as solutions 

 of alumina are distinguished from those substances. From solutions 

 of alumina and glucina, those of yttria are distinguished by producing 

 with a solution of potash, a precipitate which does not redissolve in an 

 excess of potash. Yttria and thorina are distinguished by the double 

 salt produced by sulphate of potash, which if it contain thorina, is inso- 

 luble in a saturated solution of sulphate of potash, but soluble if it con- 

 tain yttria. 



c. Yttria precipitates glucina, zirconia and alumina. 



128. ZINC. Pure oxide of zinc is white. When heated it becomes 

 of a lemon yellow colour, but regains its whiteness when cold. It is 

 not volatilized by heat and readily dissolves in acids. Zinc may be 

 detected by the following tests. 



Potash, ammonia, and carhonate of ammonia produce a white gelati- 

 nous precipitate soluble in excess of the precipitant. 



Carhonate of potash. White precipitate insoluble in excess of pre- 

 cipitant, but soluble in potash or ammonia. If muriate of ammonia be 



