1825.] M. Berzelius on Uranium. 269 



douljle salt merely formed an adhering crust of small crystals, 

 which had no relation with the octahedron. 1-2 gramme of this 

 salt, heated until it began to undergo fusion, gave off 0-042 grm. 

 of pure water. The residue afforded a turbid solution in water, 

 in consequence of its being partially decomposed into a sub and 

 a super salt, but the liquid was rendered transparent by the addi- 

 tion of a few drops of muriatic acid. The oxide of uranium was 

 precipitated with ammonia, and collected upon a filter ; and as 

 it is soluble in pure water, it was washed with a weak solution 

 of sal ammoniac. Ignited, it weighed 0*623 grm. and had ac- 

 quired a green colour. The filtered liquid was evaporated to 

 dryness, and the residue was calcined, in order to expel the 

 ammoniacal salts. The sulphate of potash which remained 

 weighed 0-3515 grm. Admitting that the oxygen of the oxide 

 is to that of the oxidule as 3 : 2, and that the deficiency in the 

 analysis consisted of sulphuric acid, ihe composition of the salt, 

 according to this experiment, would be : 



Containing oxygen. Percent. 



Potash 19-00 3-23 15-833 



Oxide of uranium . . . 63-40 3'31 58-833 



Sulphuric acid 33-40 20-04 27-834 



Water 4-20 3-73 3-500 



120-00 100-000 



■ Another portion of this double salt, prepared from a solution 

 containing an excess of acid, appeared to possess exactly the 

 same crystalline form with the preceding, but its yellow colour 

 was considerably paler. On being analysed by the same pro- 

 cess with the one employed above, with this exception that 

 after the separation of the oxide of uranium, the sulphuric acid 

 was precipitated by muriate of barytes, it yielded 6-5 per cent, 

 of water, 50 per cent, of oxidule of uranium, 82 per cent, of sul- 

 phate of barytes, and 27 per cent, of sulphate of potash. This 

 IS equivalent to 



Containing oxygen. 



Potash 14-60 2-48 



Oxide of uranium 50-84 2-53 (2-65?) 



Sulphuric acid 28-20 16-92 



Water 6-50 5-78 



This experiment demonstrates that the quantity of oxygen is 

 the same in both bases, and that the salt was mixed with a 

 portion of an acid salt, which differed from it also in containing 

 a larger proportion of water of crystallization. 



M. Arfwedson found the ratio between the oxygen of the 

 oxide of uranium and of the potash to be nearly as3 : 2. Hence 

 it would appear that his salt contained a portion of sulphate of 



