THE A TOM 91 



ference what the chemical constitution of a sub- 

 stance may be, or how compKcated the phenomena 

 that are to be interpreted, or whether the phenomena 

 fall under simple chemistry or any one of the several 

 branches of physical chemistry or under biochem- 

 istry, this is the sole method of interpretation 

 that accords with the accepted view of the atom. 



It is a curious circumstance that the planetary 

 atom (to which the spectroscopic facts undoubtedly 

 testify, and that interprets well the periodic prop- 

 erties of the elements, and which therefore has 

 been generally accepted) seemingly encounters dif- 

 ficulties in connection with organic chemistry. This 

 impressively serves to emphasize the fact, which 

 chemistry always has had to deal with, that chemical 

 substances fall into two classes, the organic (carbon 

 compounds) and the inorganic. Carbon compounds 

 are much less stable than inorganic substances 

 toward physical and chemical reagents, and require 

 methods of analysis different from those employed 

 for the inorganic. Generally the molecule of or- 

 ganic substances is much heavier than the molecule 

 of inorganic substances. Indeed, the very heavy 

 molecule is one of the chief characteristics of organic 

 substances. 



The differences between substances that led to 

 their classification as inorganic and organic, are 



