1824.] M. Arftcedson on Uranium. 263 



solution of sulphate of uranium to which some sulphate of potash 

 has been added. It forms a confused crystallized mass of an 

 exceedingly beautiful lemon-yellow colour. When heated, it 

 gives out in the first place water, and when the heat is aug- 

 mented melts, and flows into a liquid. The fused salt is green- 

 ish-yellow, and therefore has probably undergone a partial 

 decomposition; although it gives a full lemon-yellow solution in 

 water ; but if the salt be heated only to a commencement of 

 fusion, it retains its yellow colour completely. 



A solution containing 2T72 grs. of crystallized and anhydrous 

 potash-sulphate of uranium was precipitated by muriate of 

 barytes. The sulphate of barytes being separated, washed, and 

 heated to redness, weighed 1-814 gr. corresponding to 0*623 

 sulphuric acid. 



The filtered liquid was saturated with caustic ammonia, which 

 precipitated uraniate of barytes. It was collected on the filter 

 and weighed. The residual liquid was mixed with a sufficient 

 quantity of sulphuric acid both to separate any barytes that 

 might remain, and in order finally to obtain a sulphate of potash 

 quite free from muriatic acid. After this the whole liquid was 

 evaporated to dryness ; the dry salt was heated to redness in a 

 weighed platinum crucible, by which the ammoniacal salts were 

 volatilized, and sulphate of potash remained, which was rendered 

 neutral by the fumes of carbonate of ammonia. It weighed 

 0*533 gr. equivalent to 0*288 gr. of potash. The salt dissolved 

 in water without residue, and the solution was neither rendered 

 turbid by ammonia, nor by nitrate of silver; showing that ft 

 contained neither oxide of uranium nor muriatic acid. The sul- 

 phuric acid and the potash were thus determined ; what is 

 wanting to make up the original quantity of salt employed must 

 be peroxide of uranium. It follows that the constituents of the 

 double salt must be : 



Sulphuric acid 0-623 



Potash 0*288 



Peroxide of uranium 1*261 



2*172 

 Or in 100 parts : 



Sulphuric acid 28*68 



Potash 13*26 



Peroxide of uranium 58*06 



100-00 



13*26 potash are saturated by 11*26 sulphuric acid. There 

 remain 17*42 acid which belong to the 58*06 of peroxide of ura- 

 nium ; but 17*42 sulphuric acid saturate a quantity of basis 

 contaiaing 3477 oxygen; 100 parts of peroxide of uranium 



