432 The Disintegration Products of Uranium. 



scarcely soluble uranium oxalate was separated from the 

 mother liquor by suction, and dissolved in a large quantity 

 of hot water. It was then filtered, evaporated to dryness, 

 and converted into the nitrate. This uranium nitrate might 

 possibly have contained traces of thorium, because the 

 thorium oxalate might have gone through the filter-paper. 

 Therefore some inactive rare earth was added and separated 

 as above. 



After these separations, BaS0 4 was precipitated three 

 times in the uranium solution with the object of separating 

 radium and mesothorium if present. Then a mixture of 

 lead and bismuth was added and precipitated with H 2 S to 

 separate polonium if present, and finally uranium was twice 

 crystallized as nitrate. 



The first method was employed for the separation of 

 actinium, and is convenient because of the considerable solu- 

 bility of uranium oxalate in ammonium oxalate. The second 

 method, although very difficult because of the small solubility 

 of uranium oxalate in water, w^as employed to separate with 

 thorium both actinium and ionium. 



Both preparations of uranium showed only the growth of 

 UrX and the product with the period 1/5 days. All these 

 precautions were necessary since the method used for the 

 separation of UrX separates in addition actinium and its 

 products, thorium X, mesothorium and polonium. 



Summary* 



{a) It lias been shown that a product called UrY with a 

 period 1*5 days is always present in small quantities 

 in uranium. It emits soft /3 rays with an absorption 

 coefficient /jl=300 (cm.) -1 and probably also some 

 a rays. 



(&) In its chemical nature the product is very similar to 

 UrX, and it has not been found possible to separate 

 it chemically from the latter. 



(<?) The experimental results described in this paper indi- 

 cate that UrY is a lateral disintegration product of 

 uranium and is produced in small quantity compared 

 with UrX. 



In conclusion, I wish to express my best thanks to 

 Professor Rutherford for placing the necessary facilities at 

 my disposal, and for the interest he has taken in the w^ork. 



University of Manchester, 

 June 1911. 



