326 
RADIO-ACTIVE PROCESSES 













Final product 



io ] 
Radio-active r Nature of | Chemical and Physical 
Products 5; the Rays | Properties 
| | 
URANIUM | a | Soluble in excess of ammo- 
| | nium carbonate 
Uranium X | 3:6x10-7 22 days | 6 (and y?) | Insoluble in excess of am- 
y monium carbonate 
Final product 
| 
ae ere a Insoluble in ammonia 
Thorium X 2°0 x 10-* 4 days a (and 8?)| Soluble in ammonia 
| Thorium Emanation 1:15 x10 1 minute a Behaves like a chemically 
inert gas of heavy mole- 
y cular weight. Condenses 
at — 120°C, 
Emanation X , Attaches itself to the sur- 
(first change) 2:2x 10-4 | 55 minutes | no rays face of bodies concen- 
| trated on the cathode 
} | in an electric field 
| Soluble in some acids and 
Second change | 1°74x1075 11 hours a, By y notin others. Possesses 
| well-marked chemical 
4 | properties in solution 
Final product 
RADIUM a 
| | | 
| Radium Emanation |2:14x10-*to| 3-7 to 4 days | a | Behaves like a chemically 
2-00 x 10~® | inert gas of heavy mole- 
! | cular weight 
Emanation X | Condenses at — 150° C, 
(first change) about4x1073| about 3 a |, Attaches itself to the sur- 
minutes face of bodies; mainly 
y concentrated on the 
Second change 3°18x 10-4 | 36 minutes | norays | cathode in an electric 
| {field 
Third change 4-1x10-4 | 28 minutes! a, 8,y | | Solublein someacidsand 
| not in others; volati- 
4 lized at a white heat 
Fourth change 200 years (?) a, B Soluble in sulphuric acid 

~ 
in emanation X of radium may possibly be the radio-active con- 
stituent present in the polonium of Mme Curie or the radio-tellu- 
rium of Marckwald. 
After the disintegrated radio-atoms have 
undergone the succession of changes mentioned above, a final 
stage will be reached where the atoms are either permanently 
stable or change so slowly that it is difficult to detect their 


