CONTENTS 



CHAPTEE I 



lONIZATION BY NEGATIVE IONS 



SECTION PAGE 



1. Variation of current with electric force .... 1 



2. Variation of current with distance between the elec- 



trodes when the force is constant .... 3 



3. Determination of from experiments with ultra-violet 



light 5 



4. Determination of a from experiments with Eontgen 



rays 7 



5. Conductivity produced by Eontgen rays in a gas 



between cylindrical electrodes . . . .. .11 



6. Negative ions generated by various methods have the 



same ionizing power 13 



7. Comparison of the masses of negative ions in liquids 



and gases; corpuscular state 15 



8. Eepresentation of the values of by a single curve . 17 



9. Agreement between the experimental results and the 



equation |=y(-J. . 18 



10. Properties of the curves - = /7 J . . . .21 



11. Maximum value of a ; mean free path of negative 



ions 22 



12. Comparison of the values of a with the expression 



__NV 

 Ne X 24 



