14 CHEMICAL STATICS 



It is very important, however, that it was developed inde- 

 pendently in the region of physics, and that the relations 

 between molecular weights so formed could be brought into 

 perfect harmony with those obtained on chemical grounds. 

 Starting from these hypotheses on the nature of matter, 

 and bearing in view the aim of explaining differences of 

 properties when the qualitative and quantitative compo- 

 sition is the same, we have first to consider molecular 

 weight, and the special kind of isomerism that is referred 

 to differences of molecular weight, i. e. polymerism. Next 

 comes the internal structure of the molecule, with the 

 differences so arising, and associated with the phenomenon 

 of isomerism in the narrower sense. Finally comes the 

 arrangement of molecules to form crystalline figures whose 

 differences constitute the phenomenon of polymorphism or 

 physical isomerism. Accordingly the following division 

 is adopted: 



I. Molecular weight and polymerism. 

 II. Molecular structure and isomerism. 

 III. Molecular grouping and polymorphism. 



