Disintegration Products of Uranium. 131 



It is difficult at the present time to draw any very definite 

 conclusion of the connexion of UrY with the uranium series, 

 but the general results indicate strongly that UrY is not a 

 product in the main series, but is a branch product of uranium. 



Purification of Uranium. 



100 gr. of uranium nitrate were taken and BaCl 2 was 

 precipitated in it several times as BaSO^. Subsequently the 

 uraninm nitrate solution was evaporated to dryness and kept 

 at 110° C. It was then extracted with dry ether and 

 crystallized three times as nitrate. Some ferric oxide was 

 added to the above uranium nitrate solution and separated 

 after boiling. It was found by measuring the decay curve 

 that a considerable amount of soft rays not belonging to 

 UrX was present. From the above curve the decay curve 

 of UrX was subtracted. The resultant decay curve was of 

 the same nature as the one obtained when ferric oxide was 

 added and separated from an actinium solution. It was, 

 therefore, very probable that actinium was not separated by 

 the ordinary extraction with ether. 



The following method was afterwards employed. A kilo- 

 gram of uranium nitrate was taken and BaS0 4 was precipi- 

 tated in it three times. Since actinium and lanthanum are 

 precipitated together, 10 gr. of lanthanum nitrate were added 

 to the uranium solution and precipitated by adding an excess 

 of a hot solution of ammonium oxalate. After 24 hours 

 the precipitate of lanthanum oxalate was filtered off, and 

 the uranium twice ciwstallized as double ammonium uranium 

 oxalate. Then the uranium was again converted into nitrate 

 and 10 gr. of lanthanum nitrate were again added. The 

 solution was evaporated to dryness, kept at 110° C, and the 

 uranium was extracted with dry ether and crystallized twice 

 as nitrate. The lanthanum was found to be very active. 

 It was converted into nitrate and boiled with an excess of 

 Na 2 S 2 3 . The precipitated sulphur entrained UrX, and after 

 ignition a strong preparation of UrX, without a visible 

 amount of weighable substance, was left. After six months 

 a part of the above uranium, converted into oxide, was placed 

 on a tray 18 x 18 cm., and a plate of the same size connected 

 with the negative pole of a battery placed above it, for 24 

 hours. No traces of actinium or thorium active deposit 

 could be detected on the plate. 



Another kilogram of uranium nitrate was treated in a 

 different way. To it was added some thorium from which 

 mesothorium had been separated, and afterwards an excess 

 of a hot solution of oxalic acid. After a few days the 



