92 WHAT 18 LIFE 



found to coincide roughly with the broad classifica- 

 tion of substances as polar and non-polar.^ Gilbert 

 N. Lewis describes them thus: 



"The very striking differences in properties 

 between the extreme polar and the extreme non- 

 polar types are summarized in the following 

 table . . . . : 



Polar Non-polar 



Mobile Immobile 



Reaction Inert 



Condensed structure Frame structure 

 Tautomerism Isomerism 



Electrophiles Non-electrophiles 



Ionized Not ionized 



Ionizing solvents Not ionizing solvents 



High dielectric constant Low dielectric constant 

 Molecular complexes No molecular complexes 

 Association No association 



Abnormal liquids Normal liquids. "^° 



These, then, are the various peculiarities and char- 

 acteristics that offer special difficulties and that, all 

 of them — not differences of state caused by tem- 

 perature and pressure conditions — must find their 

 ultimate interpretation in terms of the structure of 



' See Gilbert N. Lewis, Journal American Chemical Society, XXXV; and 

 W. Kossel, Annalen der Physik, XLIX. 



^^ Journal American Chemical Society, XXXVIII. 



