18 URANIUM, ANTIMONY, CHROMIUM, &c. 



uranium. I shall show immediately that it con- 

 tains li atom of sulphuric acid united to 1 atom 

 of peroxide of uranium. Let us see, therefore, 

 what the atomic weight of peroxide of uranium 

 will be, if we consider 17*158 as representing li 

 atom of sulphuric acid, and 58*305 as represent- 

 ing 1 atom of peroxide of uranium. It is ob- 

 vious, that two-thirds of 17*158 or 11-439 must 

 in that case represent 1 atom of sulphuric acid. 

 Now, 11-439 : 58-305 : : 5 : 25-486 = atomic 

 weight of peroxide of uranium. This is some- 

 what under the truth, as will appear immediate- 

 ly y though it would have been very difficult to 

 have come nearer by Arfwedson's method of 

 analysis ; for a portion of the peroxide of ura- 

 nium precipitates with the sulphate of barytes. 

 This caused him to overrate the quantity of sul- 

 phuric acid, and consequently to underrate, by 

 at least as much, the peroxide of uranium in the 

 salt. 



5. I shall now relate the experiments which 1 

 made on this salt. 



er! The peroxide of uranium which I employed 

 - to prepare it was in the state of carbonate. It 



phate of 



uranium by had been thrown down from nitric acid by car- 



the author. . .. _. / 



bonate of ammonia, and I could not discover 

 any ammonia in it, either by the smell or by any 

 other reagent, when it was digested with caustic 

 potash. Its constituents, by the most careful ana- 

 lysis of it which I could make, appeared to be 



16 



