Barss — Ionization by Collision in Gases and Vapors. 237 



400 800 1200 



800 1200 



Fig. 6. Ethyl chloride. 



40 



o 

 .2 



20 



10 



400 800 



200 400 600 



Fig. 7. Ether. 



400 



200 400 600 



800 



Fig. 8. Methyl iodide. 



200 300 600 



■> Volts per centimeter. 



