CONTENTS. 



CHAPTER I. Results with an Objective Method of Showing Distribu- 

 tions of Nuclei Produced by the X-rays or Other Radiation. 



PAGE 



1. Introductory i 



2. Apparatus i 



3. Vertical radiation at one end of the trough, entering through wood 2 



4. Axial radiation entering one end of the trough 3 



5. The same continued for larger pressure differences 4 



6. Condensation of dust-free moist air in the absence of X-ray nuclei. 



Fog limit 4 



7. Possibility of producing nuclei by sudden intense exhaustion 5 



8. Successively increasing times of exposure to X-radiation 6 



9. Symmetrically graded sizes or numbers of fog particles 7 



10. Possible origin of nuclei at the walls of the receiver 9 



11. Absorption of ions at the walls of the receiver 10 



12. Summary 10 



13. Tentative experiments with lead screens, inside and outside the fog 



chamber n 



14. The same continued, with change of apparatus 13 



15. Conclusion 16 



CHAPTER II. Numbers and Gradations of Size of the Efficient Nuclei in 

 Dust-Free Air, Energized or not by X-Ray or Other Radiation. 



EXPERIMENTS WITH DUST-FREE AIR NOT ADDITIONALLY ENERGIZED. 



16. Apparatus 17 



17. Manipulation. Fog limit 18 



18. Alternations of large and small coronas (periodicity) 18 



19. Effect of lapse of time on the nucleation of dust-free air imprisoned in 



the fog chamber 21 



20. Effect of pressure difference on exhaustion 22 



21. Remarks on the tables 25 



22. Blurred coronas 27 



23. Time effect 27 



24. Oscillations at variable pressure differences 27 



25. Nucleations at varying pressure differences 27 



26. Fog limits 28 



27. Oscillations at fixed pressure differences 29 



28. Undersaturation 29 



29. Undersaturation continued 30 



30. Nucleation 31 



EXPERIMENTS WITH DUST-FREE AIR ENERGIZED BY RADIUM. 



31. Effect of radium in hermetically sealed glass tube 3 2 



32. Remarks on the tables 35 



33. Data for nucleation 36 



34. Fog limits raised by weaker ionization 37 



vii 



