fl08 



Dr. B. B. Boltwood on 



0*007 per cent, of -uranium. Owing to the small proportion 

 in which the uranium was present, its analytical determination 

 was not attempted. 



The localities from which the specimens were obtained, 

 the reagents used for decomposing the minerals in the 



reagents 

 determination of the 

 uranium indicated by 

 which follows : — ' 



emanation, and the 

 the analysis, are 



percentages oi 

 en in the table 



No. 



Substance. 



1. 



Uraninite, 



2. 



Uraninite, 



3. 



Gummite, 



4. 



"Uraninite, 



5. 



Uranophane, 



6. 



Uraninite, 



7. 



Uranophane, 



8. 



Thorogummi te, 



9. 



Carnotite, 



10. 



Uranothorite, 



11. 



Samarskite, 



12. 



Orangite, 



13. 



Euxenite, 



14. 



Thorite, 



15. 



Ferguson ite, 



16. 



iEschynite, 



17. 



Xenotiine, 



18. 



Monazite, 



19. 



Monazite, 



20. 



Monazite, 



21. 



Monazite, 



22. 



Allanite, 



Locality. Reagent used 



North Carolina... Dilute HN0 3 



Colorado „ HN(X 



North Carolina... „ HC1 



Joachimsthal ... ,, HN0 3 



North Carolina... „ HC1 



Saxony „ HN0 3 



North Carolina... ,, HC1 



North Carolina... „ HC1 



Colorado „ HN0 3 



Norway „ HC1 



North Carolina... Concentrated H. 



Norway Dilute HC1 



Norway Cone. H 2 S0 4 



Norway Dilute HC1 



Norway Cone. H 2 S0 4 



Norway ,, H^S0 4 



Norway „ H;S0 4 



North Carolina... „ H~S0 4 



Norway ,. H^S0 4 



Brazil „ H~S0 4 



Connecticut „ H S0 4 



North Carolina... „ H~S0 4 



Per cent. 

 Uranium. 



74-65 

 69-61 



65-38 



61-74 



51-68 



50-64 



49-84 



33-17 



2261 



11-38 



10-44 



10-34 



871 



7-54 



557 



4-52 



0-70 



0-43 



0-41 



0.31 



0-30 



(estimated) 0"007 



,S0 4 



The following table shows the results which were obtained 

 in the examination of these minerals. Column I. gives the 

 activity of the emanation contained in 1 gram of the mineral ; 

 Column II. the activity of the emanation lost by 1 gram 

 of the mineral at ordinary temperatures ; Column III. the 

 sum of the two previous activities (total emanation equivalent 

 to the radium contained in 1 gram of the mineral) ; Column 

 IV. the percentage of the total emanation lost by diffusion 

 from the cold mineral (the emanating power of the mineral 

 at ordinary temperatures) ; Column V. the weight (in grains) 

 of the uranium contained in 1 gram of mineral ; Column VI. 

 the ratio of the radium to the uranium (the number obtained 

 on dividing the total activity — Column III. — by the quantity 

 o£ uranium — Column V.). 



From the data given in the table it is evident that 

 a direct proportionality (within the limits of experimental 

 error) exists between the quantities of radium and the 

 quantities of uranium, and the inevitable and only possible 



