CONTENTS. 



CHAPTER I. Nuclei of Pure Water. 



Page. 



1 . Introductory i 



2. Rapid evaporation of fog particles. Phosphorus nuclei. Table i ; fig. i i 



3. Spontaneous evaporation of fog particles. Phosphorus nuclei. Table 2 3 



4. Slow spontaneous evaporation of fog particles. Vapor nuclei. Table 3 4 



5. Rapid evaporation of fog particles. Vapor nuclei. Table 4 7 



6. Evaporation retarded as the diameter of fog particles decreases 8 



7. Time losses. Table 5 8 



8. Effect of changes of the drop of pressure 10 



9. Exceptionally rapid evaporation 1 1 



10. Conclusion 1 1 



11. The same, continued 12 



1 2. The same, continued 13 



13. The same, continued 13 



14. Statistical hypothesis 14 



CHAPTER II. Standardization and Efficiency of the Fog Chamber. 

 AXIAL COLORS AND INTERFERENCES. 



15. Introductory 15 



1 6. Causes of axial colors. Table 6 15 



17. The lamellar grating 16 



1 8. Disk colors of coronas 16 



19. Experiments with long tubes. Table 7 ; fig. 2 17 



20. Short tubes. Table 8 19 



CORONAS WITH MERCURY LIGHT. 



2 1 . Preliminary survey 20 



22. Apparatus 21 



23. Equations 21 



24. Data with white light. Table 9; fig. 3 22 



25. Data with green mercury light. Tables 10 and 1 1 ; figs. 4 to 9 24 



26. Inferences. Interference and diffraction. Table 12 31 



EFFICIENCY OF LARGE AND SMALL FOG CHAMBERS ATTACHED TO THE 



SAME VACUUM CHAMBER. 



27. Fog chambers 33 



28. Data. Table 1 3 ; fig. 10 34 



29. Data for apertures. Table 14; fig. 1 1 37 



30. Results 39 



3 1 . Conclusion 39 



CHAPTER III. Regions of Maximum lonization and Miscellaneous 



Experiments. 



REGIONS OF MAXIMUM IONIZATION DUE TO GAMMA RADIATION. 



32. Introductory 41 



33. Short fog chamber 41 



34. Behavior after removal of radium 42 



35. Long fog chamber 43 



36. Data. Table 1 5 ; figs. 1 2 to 1 5 43 



37. Inferences 47 



VII 



1 1 



