15. Dust Particles or Rust on the GORDON Electrodes Hasten Discharge. 16. Where the Distance is Greater, the THOMSON Dielectric Strength is Smaller, Both (KELVIN) Distances Being Minute. 17. Discharge through Gases under Very High CAILLETET Pressures. Increased Dielectric Strength. 18. Discharges in Different Chemical Gases FARADAY Variably Resisted. 19. Gas as a Conductor. Molecule for THOMSON, J. J. Molecule, its Conductivity Greater than that for Gases. 20. Relation of Light to Electricity. The BOLTZMANN, Square Root of the Dielectric GIBSON, Capacity Equal to the Refractive BARCLAY, Index. HOPKINSON, and GLADSTONE 21. Hermetically Sealed Discharge Tubes PLÜCKER and with Platinum Leading-in Wires. GEISSLER 22. Luminosity of Discharge Tubes Produced GEISSLER by Rubbing. Increased by Low Temperature. 23. Different Vacua Needed for Luminosity ALVERGNIAT by Friction and by Discharge. 24. Phenomena of Discharge around the Edges STEINMETZ of an Insulating Sheet. 25. Highest Possible Vacuum Considered as a MORGAN Non-conductor. 26. Constant Potential at the Terminals of DE LA RUE and a Discharge Tube. MÜLLER 26_a_. Polarity of Discharge-tube Terminals in KLINGENBERG Secondary of Ruhmkorff Coil. Mathematical Deductions. 27. Pressure in Discharge Tube Produced by KINNERSLEY, a Spark. HARRIS, and RIESS CHAPTER II. 28. Actions of Magnetism upon the Arc and DAVY, Flame. BANCALARI, and QUET 29. Rotation of Luminous Discharge by a DE LA RIVE Magnet. Application in Explaining Aurora Borealis. 30. Action of Magnet on the Cathode Light. PLÜCKER and Relations Different according to the HITTORF Position Relatively to the Magnetic Lines of Force. 31. Discharge Retarded Across, and THOMSON, J. J. Accelerated Along, the Lines of Magnetic Force. 32. Resistance of Luminosity of the THOMSON, J. J. Discharge Afforded by a Thin Diaphragm.