240 Bolt wood — Production of Radium from Uranium. 



paper, published May 12, 1904, very scanty details of the 

 experimental procedure are given, but a summary of the con- 

 clusions reached at that time by the author is as follows : 



1. The quantity of radium which has accumulated in one 

 kilogram of uranium nitrate in twelve months is less than 10~ n 

 gram. 



2. The question so far as the production of radium from 

 uranium is concerned is practically settled. 



3. If uranium changes into radium, less than one ten-thou- 

 sandth part of the theoretical quantity is produced during the 

 first year's accumulation. 



4. The evidence may be taken as indicating that uranium is 

 not the parent element of radium. 



The second paper, published Jan. 26, 1905, eighteen months 

 from the commencement of the experiment, is likewise lacking 

 in a detailed account of the experimental methods, but the 

 author states that measurements carried out at that time with 

 the kilogram of uranium nitrate under observation indicate 

 that it contains 1*5 XlO -9 gram of radium, a quantity which, 

 while of considerable relative magnitude, is only one live-hun- 

 dredth of the amount to be expected from the disintegration 

 theory on the assumption of a direct change. The author 

 suggests that the greater part of the radium emanation may 

 (under the conditions of the experiment) be retained in the 

 uranium solution and not evolved as a gas. On the basis of 

 the amount of radium assumed to be then present it is deduced 

 that the fraction of uranium changing per year is 2 XlO" 12 . 



After pointing out certain sources of error likely to have 

 exercised a disturbing influence during the elapsed period of 

 observation, the author adds, — "if the whole series of meas- 

 urements from the commencement are recalculated, eliminat- 

 ing the error alluded to, they are fairly consistent with there 

 having been a steady production of radium at this rate contin- 

 uously from the commencement." One of the sources of 

 error alluded to was the introduction of very considerable 

 quantities of radium salts into the laboratory during the 

 period when the kilogram of uranium nitrate was under obser- 

 vation. It is stated that the presence of this radium greatly 

 disturbed the electroscope in which the measurements were 

 conducted. Additional difficulty had been previously experi- 

 enced in attempting to standardize the measuring instrument 

 with the emanation corresponding to a known weight of pure 

 radium salt. 



that he also believes that he has observed indications of the growth of 

 radium in uranium compounds. Since Whetham's communications contain 

 neither any account of experimental details nor any record of quantitative 

 measurements, it is impossible to judge as' to the value of the data on which 

 the author's conclusion is based. 



