Discharge of Electricity from Cylinders and Points. 789 



The real difficulty is not to explain why some unsaturated 

 compounds exist, but why others of analogous chemical 

 constitution are not found in the free state. Thus, for 

 example, it is not so much the existence of CO that requires 

 explanation as the fact that while in this compound the 

 carbon atom exerts so little attraction on another carbon 

 atom that the compound = = C = is not found, in CH 2 

 the carbon atoms have so much affinity for other carbon 

 atoms that CH 2 does not under ordinary circumstances exist 

 ill a free state (though it is found in vacuum tubes) but at once 

 unites to form the compound C 2 H 4 . Or, to take a case still more 

 analogous, since in CO the carbon is combined with a more 

 electronegative element, why is not CC1 2 found in a free state ? 

 I think we can see a reason for this difference, if we 

 remember that each atom even when saturated produces a 

 strong electric field in its neighbourhood, and that this field 

 will tend to restrict the freedom of motion of the corpuscles 

 in a neighbouring atom. Thus, if the electric field due to 

 the oxygen atom in CO were very strong, then though only 

 two out of the four mobile corpuscles in the carbon atom 

 are bound by tubes of force to the oxygen atom, the other 

 two would be exposed to a strong electric field and would 

 have their mobility thereby reduced, and in consequence 

 the attraction of the carbon atom on other atoms would be 

 diminished. The diminution in the attraction would depend 

 upon the strength of the electric field in the carbon atom 

 due to the oxygen atom. If the field exerted by the two 

 hydrogen atoms in CH 2 , or the two chlorine atoms in CC1 2 , 

 were smaller than that exerted by the oxygen atom in CO, 

 then the carbon atom in CO would be much more nearly satu- 

 rated than the ones in CH 2 or CC1 2 , and so the former molecule 

 might exist in a free state while the others could not. 



LXXXIX. The Discharge of Electricity from Cylinders 

 and Points. By Professor J. S. Townsend, M.A., New 

 College, Oxford, and P. J. Edmunds, B.A., Queen's College, 

 Oxford*. 



1. npHE discharge of electricity through gases in those 

 JL cases where the electric field is not uniform is 

 attended by phenomena which are absent in the case of the 

 uniform fields produced between plane electrodes. The case 

 in which the electrodes are concentric cylinders has been 

 chosen by various investigators as showing these phenomena 



* Communicated by the Authors. 

 Phil. Mag. S. 6. Vol. 27. No. 161. May 1914. 3 Q 



