264 M. Arfivedson on Uranium. [April, 



consequently contain 5*99 oxygen ; or 100 parts of the metal, in 

 order to beperoxidized, combine with 6*37 oxygen. 



The oxygen of the potash is to that of the peroxide of uranium 

 as 2 to 3 ; for the oxygen in 13*26 potash is 2*248, and in 58*06 

 of peroxide of uranium 3*477. Now 2*248 : 3*477 :: 100 : 

 154*7. 



If we now collect the results of all these experiments to deter- 

 mine the quantity of the oxygen in the peroxide, we shall find 

 them as follows : 



100 parts of uranium take up, according to the analysis of 



Oxygen. 



Uraniate of lead 5*559 



Uraniate of barytes 6*340 



Potash-sulphate of uranium 6*370 



The number 5*559 has almost the same ratio to the oxygen in 

 the protoxide that 3 has to 2 ; for in the protoxide 100 parts of 

 uranium are combined with 3*688 parts of oxygen, which, mul- 

 tiplied by li, = 5*532 ; but the last two numbers lie between 

 1^ and twice 3*688. It is difficult to determine which of these 

 numbers come nearest the truth. The last two, although 

 obtained different ways, accord in a remarkable degree ; and 

 have in consequence some claim to be considered as accurate. 

 But on the other side it is clear that the experiments made with 

 uraniate of lead ought to come out with greater precision ; 

 because the analytical method followed with respect to it puts it 

 in our power to attain a higher degree of accuracy than is likely 

 in the two following experiments. I must in the mean time 

 acknowledge that these experiments do not furnish us with the 

 knowledge of the composition of the oxides of uranium with that 

 degree of accuracy which chemists have a right to require. At 

 the same time it may be admitted as most likely that the oxygen 

 in the peroxide of uranium is 1^ times as great as in the protox- 

 ide ; unless we were to admit that the second composition, such 

 as it was found, can be completely depended on ; and this there 

 is not much reason to do, as both the oxidizement of the metal 

 and the reduction of the protoxide, give the same composition of 

 the oxide. 



According to M. Schonberg's experiments on the composition 

 of the oxides of uranium,* the oxygen in the protoxide is to that 

 in the peroxide as 2 to 3 • for he found the protoxide to contain 

 6, and the peroxide 8*73 per cent. The oxygen in the protoxide 

 was determined by analysing the protomuriate of uranium • and 

 the composition of the peroxide was determined by the loss of 

 weight which it sustained when heated to redness, by which it 

 was converted into protoxide. But it appears from my experi- 

 ments, that the protomuriate can never be obtained neutral and 



* De conjunctione chemica ejusque ratiojiibus. Upsalke, 1813. 



