THE CLASSIFICATION OF CARBON COMPOUNDS. 

 By MARSTON TAYLOR BOGERT. 



(Read April 20, 19 12.) 



The system of classification adopted for a science at any given 

 period registers quite accurately the state of the science at that 

 period, and the changes in the classification therefore record its 

 progress. It is, hence, practically impossible to give any intelligible 

 description of the various methods of classification which have been 

 employed for carbon compounds without at the same time sketching 

 briefly the changing conceptions and theories of which they were to 

 so large an extent the natural reflection, for without such a setting 

 the picture would have no proper background or perspective. 



The classifications which are considered are particularly those 

 which have been used for textbook instruction in organic chemistry, 

 and no place is given to those which have been devised solely for 

 the patent ofiices, for reference, or for other special purposes. 



Man being naturally of an inquiring mind, he has probably 

 speculated upon the composition of this world of ours ever since he 

 first appeared upon it, for in the oldest records we find theories 

 concerning the elements of which it is composed. 



The doctrine of the four so-called " elements " — earth, air, fire 

 and water — was first enunciated in Greece by Empedocles, about 

 440 B. C, but generally bears the name of Aristotle. Neither 

 Empedocles nor Aristotle regarded these elements as different forms 

 of matter, but rather as different properties or manifestations of 

 one original matter. Aristotle also added a fifth element, ovaia, 

 to which he ascribed an ethereal or immaterial character and which 

 he assumed permeated the universe. As the oldest writings of 

 India contain a similar theory of four elementary principles and an 

 ethereal substance, it is possible that both Aristotle and Empedocles 



252 



