ALLOTROPISM BASED ON THE THEORY OF DIRECTIVE VALENCY. 323 



4. In which four neighbouring bonds representing cor- 

 puscles travelling in one direction (a) are followed 

 by four travelling in the opposite direction (b), 

 represented by the formula (a a a a b b b b). 



Case 1 is represented by the graphic formula : — 

 , x o o 



v v 



T { 



Each atom has lost a corpuscle (a unit of negative elec- 

 tricity) to one of the neighbouring atoms and has gained 

 one from the other neighbouring atom, the result being a 

 symmetrical stable molecule in which the electrical charge 

 on each atom is neutralized. 



Case 2 is represented as follows : — 



(2) >-»S_ 2 



T i 



+2 S -»S_ 2 



s«— S 



-2 W W +2 



In this case each alternate atom receives two negative 

 corpuscles, acquiring two unit charges of negative elec- 

 tricity, and loses two negative corpuscles, acquiring two 

 unit charges of positive electricity, the result being a 

 symmetrical stable molecule in which the electrical charge 

 is evenly distributed. 



