LIST OF ILLUSTRATIONS. 



PAGE 



FIG. i. Fog chamber with appurtenances and X-ray bulb, X 2 



2-6. Diagram of a succession of distorted coronas ^ 



7. Computed curves 8 



8-10. Forms of lead screens T ! 



11-12. Fog chambers with screens and X-ray bulb 14 



13. Fog chamber with axial and oblique radiation 15 



14-18. Graphs showing the alternations of the apertures (s) of corona 



in non-energized dust-free air 21 



19. Decay of the nuclei examined in the lapse of hours 21 



20-25. Change of apertures (,y) of coronas and number of efficient 

 nuclei () varying with the different pressure differences for 



the cases of superior and inferior coronas 26 



26. Number of efficient nuclei (n) obtained in successive exhaus- 

 tions of dust-free air energized by radium 34 



27-30. Change of aperture (.y) of coronas and nucleations (n) vary- 

 ing with the pressure differences in cases of dust-free air 



energized or not by radium (in sealed glass) 34 



31-32. Decay of the nuclei produced by radium after the removal of 



the tube from the fog chamber 34 



33.34. Apertures of coronas (j) and nucleations (n) varying with the 

 pressure differences, for the case of dust-free air energized 



by radium acting from different distances 36 



35-37- Decay curves found after the removal of the radium from the 



fog chamber 36 



38-39. Apertures (j) and nucleations (w) varying with the pressure 

 differences for the case of persistent nuclei produced in dust- 

 free air by the X-rays 43 



40. Filter with wet sponge tube (saturator) 48 



41. Rectangular wood fog chamber 48 



42. Cylindrical glass fog chamber 48 



43. Rectangular fog chamber 49 



. 44. Cylindrical fog chamber 49 



45-51. Illustrating Tables 29, 32, 33, 34, 35, 36 51 



52-55. Illustrating Tables 30, 31 54 



56-62. Illustrating Tables 37, 38 62 



63-68. Illustrating Tables 39, 40, 41 r 65 



69-78. Illustrating Tables 43, 44, 45, 49, SO, 53, 54 73 



79-82. Illustrating Table 47 76 



83-87. Illustrating Tables 47, 51, 53, 54 



88-90. Illustrating Table 56 



xi 



