1824.] M. Arfwedson on Uranium. 257 



for potash-muriate of uranium may be freed from water without 

 the least difficulty, as the salt can be exposed to a moderate red 

 heat without undergoing any decomposition. 



The experiment was conducted in the first place in an appa- 

 ratus similar to that above described. As soon as the hydrogen 

 gas began to pass, and the salt became hot, it fused and swelled 

 up, muriatic acid gas was given out, and the mass became dark- 

 coloured and opaque. Though the process was continued for 

 nearly two hours, and the heat from the Argand's spirit lamp 

 was raised to the highest degree of intensity, vapours of muriatic 

 acid still continued to pass ; a proof that the salt was not com- 

 pletely decomposed. The whole being allowed to cool, the 

 matter was extracted by water, which dissolved muriate of 

 potash, together with a good portion of uranium salt, of a light- 

 green colour. The insoluble residue was a black crystallized 

 powder having the metallic lustre, which was washed, and dried 

 upon blotting paper. 



Supposing that the heat in this experiment might have been 

 too weak, and that the salt, if exposed to a higher temperature, 

 might have been more completely decomposed, it was again 

 repeated with this difference, that the salt was put into an appa- 

 ratus, which could be more strongly heated, and which was 

 introduced half way into a small furnace heated with charcoal. 

 The heat applied was so strong that the glass was almost melted ; 

 yet the salt was not completely decomposed ; for after washing 

 the altered salt with water, there remained the same crystallized 

 matter as in the preceding experiment; but of a still more 

 decided metallic appearance ; for the salt had been employed in 

 greater quantity, and on that account the crystals were larger 

 and more distinct. The form of these crystals as seen under the 

 microscope was an octahedron very nearly regular, whose faces 

 had a very strong metallic lustre. Some of them were slightly 

 transparent at the edges, and of a reddish-brown colour; and 

 this colour remained even after the crystals Avere reduced to 

 powder. These crystals were not altered by exposure to the 

 atmosphere ; but when heated, they were reduced to powder, 

 increased in bulk, and were changed into green protoxide of 

 uranium, which, when treated with acids, exhibited the very 

 same characters as the products of the reduced protoxide. 



It is scarcely possible to think, that in this experiment an 

 oxidized body could have been obtained ; especially if the double 

 salt employed be viewed according to the new theory of the 

 nature of muriatic acid, according to which that acid contains 

 no oxygen whatever. All the circumstances taken together 

 lead to the conclusion, that the crystallized body obtained was 

 metallic uranium. Ob'36 part of it were heated in a platinum 

 vessel, and converted into green oxide. The increase of weight 

 was U-U2:$5, or 100 parts of the metal had combined with 3-(j!J/i 

 parts of oxygen. For the sake of security the oxide was dissolved 



New Series, VOL, VI I. s 



