194 URANIN1TE. 



of ammoniacal salt is volatilized, and all the sesqui- 

 oxide of uranium precipitated. 



The pure yellow precipitate, uranate of ammonia is 

 filtered off, and, when the filtrate begins to pass 

 through turbid, washed with solution of sal-ammoniac. 



When ignited, it leaves dark green proto-sesqui- 

 oxide of uranium. By digesting this with dilute 

 hydrochloric acid, any lime and magnesia may be 

 extracted. 



In order to prepare protoxide of uranium from the 

 uranate of ammonia, it is dissolved in hydrochloric 

 acid, the solution mixed with an excess of pure sal- 

 ammoniac, and about an equal quantity of pure com- 

 mon salt ; it is then evaporated to dryness, and the 

 mass heated in a covered crucible until the sal-ammo- 

 niac is volatilized, and lastly, until the common salt 

 fuses. On dissolving it in water, the protoxide of 

 uranium is left as a heavy crystalline powder. The 

 common salt only serves to shield the oxide from the 

 action of air. 



When the quantity is very small, the uranate of 

 ammonia is calcined and the proto-sesquioxide is dis- 

 solved in hydrochloric acid with a few drops of nitric 

 acid; the addition of chloride of potassium forms a 

 substance U 2 O 2 01 + R 01. It is evaporated to dryness 

 and the yellow salt ignited in a current of hydrogen. 



In order to extract from the hydrated sesquioxide 

 of iron the small quantity of sesquioxide of uranium 

 which is chemically combined with it, it is dissolved in 

 the smallest possible quantity of hydrochloric acid, 

 the solution neutralized with carbonate of ammonia, 

 and added, drop by drop, with constant stirring, to a 

 mixture of carbonate of ammonia and sulphide of 

 ammonium, when all the iron is separated as sulphide, 

 and the sesquioxide of uranium remains in solution; 

 the latter may be precipitated by boiling the filtrate. 



Or the sesquioxide of iron may be reduced in a 



