8 Wellisch — Motion of Ions and Electrons through Gases. 



For lower pressures of the gas this effect practically van- 

 ishes ; with CO, at a pressure of 4^°"° the EI curve obtained 

 after the gas had remained undisturbed in the vessel for 2 days 

 was identical with that obtained immediately after the intro- 

 duction of the gas. 



It is probable that the above effect arose from a very slow 

 leak of oxygen into the vessel from the outside atmosphere ; 

 actual experiments were performed to test this point and it was 

 found tliat traces of air added to CO^ or H^ at relatively high 

 pressures resulted in a marked decrease of the number of free 



Fig. 4. 



120 



electrons whereas when these gases were at low pressures the 

 number of electrons was not appreciably affected by the 

 admixture. 



It should, however, be mentioned that a similar though much 

 more intense effect was found in experimenting with the free 

 electrons in the vapor of petroleum ether {v. sec. 4 D) ; in 

 this instance the diminution in tlie number of electrons was 

 very rapid and could not reasonably be ascribed to a small leak 

 of air into the apparatus. All the indications pointed to the 

 appearance in the vapor of a constituent capable of absorbing 

 electrons at ordinary temperatures. It is convenient to refer 

 to nuclei, whether molecules or aggregations, which possess 

 this property, as 'electron sinks'; the electrons cannot remain 

 in the free state during their motion through a gas which con- 

 tains these sinks other than in excessively small quantity. All 



