ACTIVATION OF ELECTRICAL CONTACTS BY ORGANIC VAPORS 801 



Table IV — Benzene Decomposition in Active and 



Inactive Arcs 



Measurements 



Carbon required for full activitj' 1 



Carbon formed in active arcs 2 



Carbon formed in inactive arcs 3 



Benzene decomposed in active 4 

 arcs 



1250 erg arcs (232 volts) 



15 erg arcs (58 volts) 



2.5 X 1015 atoms 

 1.8 X 10" atoms/erg 

 5 X 10« atoms/erg 

 3.0 X 10« molecules/ 



erg 

 70 X 10-^ molecule 



per electron 



No data 



7 X 109 atoms/erg 



No data 



13 X 108 molecules/ 



erg 

 300 X 10-^ molecule 



per electron 



Calculations 



* The benzene is probably adsorbed on spongy carbon of much greater true 

 area. 



adsorption for contacts already active is doubtless due to the greater 

 surface area resulting from the presence of this carbon. 



Many of the numerical values considered here are collected in Table IV 

 for ready reference. These data refer to arcs at platinum surfaces. It is 

 our present opinion that the amount of carbon formed at silver surfaces 

 in similar experiments would be found to be only slightly smaller per 

 unit of energ}^, although unfortunately no experiments were carried out 

 upon silver. 



5.2 Inhibiting Surface Films 



One concludes from the above experiments that activation bj^ benzene 

 vapor is the result of firm adsorption of benzene molecules on the elec- 



