Chemical Science. , 183 



salt to an ounce of water, but then by the addition of a few 

 drops of prussic acid, the blue colour is immediately deve- 

 loped of great purity and intensity. This colour is not per- 

 manent, but soon passes to a green, and, at length, totally 

 disappears. In want of prussic acid, distilled laurel water, or 

 that of plum or black-cherry kernels, may be employed. This 

 re-action succeeds, when the proportion of salt to the fluid is 

 not more than a -^Isj^ : in this proportion no other test, whe- 

 ther the prussiates of potash, soda, or ammonia, will develope 

 the least indication of the presence of copper/' 



In using tincture of guaiacum, as a test for copper, care must 

 be taken that no other bodies are present which turn it blue. 

 Annates Generates dcs ScienceSf Sfc. 



13. Process for procuring pure Zirconia. — Powder the zircons 

 very fine, mix them with two parts of pure potash, and heat 

 them red hot in a silver crucible for an hour. Treat the sub- 

 stance obtained with distilled water, pour it on a filter, and 

 wash the insoluble part well ; it will be a compound of zirconia, 

 silex, potash and oxide of iron. Dissolve it in muriatic acid, 

 and evaporate to dryness, to separate the silex. Re-dissolve 

 the muriates of zirconia and iron in water ; and to separate the 

 zirconia which adheres to the silex, wash it with weak muriatic 

 acid, and add it to the solution. Filter the fluid, and preci- 

 pitate the zirconia and iron by pure ammonia ; wash the preci- 

 pitates well, and then treat the hydrates with oxalic acid, boil- 

 ing them well together, that the acid may act on the iron, re- 

 taining it in solution whilst an insoluble oxalate of zirconia is 

 formed. It is then to be filtered, and the oxalate washed, until 

 no iron can be detected in the water that passes. The earthy 

 oxalate is when dry of an opaline colour; after being well 

 washed, it is to be decomposed by heat in a platinum crucible. 



Thus obtained, the zirconia is perfectly pure, but is not 

 affected by acids. It must be re-acted on by potash as before, 

 and then washed until the alcali is removed. Afterwards dis- 

 solve it in muriatic acid, and precipitate by ammonia. The 

 hydrate thrown down, when well washed, is perfectly pure, 

 and easily soluble in acids. 



