Figs. 1- 3. Flame noii-luminous, electricity on disc positive. Figs. 7- 9. Flame luminous, electricity on disc positive. 
Figs. 4- 6. » » ./ i/ negative. Figs. 10-12. » » ,/ „ negative. 
Figs. 1-12. Height of Flame constant. 
Figs. 13-16. Flame non-luminous, electricity on disc positive. Figs. 19-21. Flame luminous, electricity on disc positive. 
Figs. 16-18. u u n n negative. Figs. 22-24. » <. * » negative. 
Figs. 13-24. Distance of tube from disc constant. 
